......... faster than comparable petrol-engined cars?
I read lots of opinions that diesel cars accelerate faster than petrol cars of similar engine capacity, but nobody ever gives any proof. So ............ here's your chance. Car model, engine capacity and type, acceleration times, and source of information.
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Its because people always talk about in gear acceleration
That's the 50-70 or 30-60 without changing gear acceleration. Its the most useful acceleration available and most widely used on the road, yet few magazines measure it
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>>similar engine capacity
Is engine capacity the best measure to use to gauge equivalence though?
Wouldn't it be more appropriate to compare cars of equivalent fuel consumption for example?
Air is (as I type) free, but, fuel isn't.
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Could you define 'accelerate'? Because as I understand it (no figures) the 0-60 time will be slower but for example the 30-50 in top will be quicker.
EDIT: as Z said, sort of
Last edited by: Focus on Thu 10 Mar 11 at 09:16
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>> Could you define 'accelerate'? Because as I understand it (no figures) the 0-60 time will
>> be slower but for example the 30-50 in top will be quicker.
You can choose whatever speed range you like. I'm just asking for proof, and so far it's not been forthcoming.
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>> You can choose whatever speed range you like. I'm just asking for proof, and so
>> far it's not been forthcoming.
That car that overtakes you? Its a diesel. There's your proof.
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>> That car that overtakes you? Its a diesel. There's your proof.
>>
I've not seen that yet!
Signed: L'escargot by name but not by nature.
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Anyone who says diesels don't have a useful real-world advantage doesn't know what they are torquing about.
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>> Anyone who says diesels don't have a useful real-world advantage doesn't know what they are
>> torquing about.
You're just doing what every diesel freak does, which is to give your opinion without any proof to back up what you've said. I'm just asking for the unbiased proof.
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...You're just doing what every diesel freak does....
L'escargot,
Diesels accelerate faster in gear than equivalent petrols.
It's simply a matter of fact.
You don't want to accept that fact, fine.
Buy a petrol.
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>> It's simply a matter of fact.
Prooooove it ;-) 1.6 diesel focus vs. 1.6 ecoboost petrol ?
Petrol wins in every combination of in gear, or different starting / ending speeds.
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>> Diesels accelerate faster in gear than equivalent petrols.
>>
>> It's simply a matter of fact.
No, it's a matter of your opinion. Simply saying that they accelerate faster doesn't make it a fact. Give me figures.
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Don't know whether they do or don't but you can easily look them up yourself.
www.carspecsdirectory.com/
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OK if this works this link is to What Car with a comparison set up between a Citroen C3 1.4 petrol and diesel...
tinyurl.com/6h2kvze
Random facts... Diesel model costs £1000 more to buy. BHP very similar but diesel has 30% more torque. Diesel fuel consumption 15-20mpg better across the useage types. Diesel is 0.5sec quicket to 60mph. Top speeds the same.
I'm not calling that proof... just a comparison.
Last edited by: Fenlander on Thu 10 Mar 11 at 09:28
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>> OK if this works this link is to What Car with a comparison set up
>> between a Citroen C3 1.4 petrol and diesel...
BHP very similar but diesel has
>> 30% more torque.
Quoted engine output torque perhaps, but the difference in torque at the driving wheels will be reduced by virtue of the higher gearing of the diesel.
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I'm not sure what point you're trying to make... I just offered a comparison from an independent source.
In gear times are the answer to how a car feels on the road though as said above. Years ago (70s) they were part of the Autocar & Motor road tests. I remember my Saab 99 Turbo was one of the fastest 60-80mph (top gear) cars in the 80s.
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Source: www.zeperfs.com/duel2674-1357.htm First time i've said "excuse the french" and meant it literally ;-)
2.0 Diesel Octavia Vrs vs. 2.0 Petrol Octavia Vrs. Same drag co-efficients but different weights (diesel obv heavier). Diesel has quite a lot more torque, petrol has more power.
80-100 km/h in 6th gear, diesel 5.9 secs, petrol 4.3 secs
80-180 km/h through the gears, diesel 23.3 secs, petrol 17.4 secs
0-160 km/h, diesel 23.3 secs, petrol 16.8 secs
Fuel economy for comparison, diesel combined 49.6mpg, petrol combined 37.7mpg. Source: skoda.co.uk/GBR/Documents/brochures/cars/brochure_octavia.pdf
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There you have it. One of two relevant posts in the thread, and it does show that this petrol cars is quicker than the diesel equivalent.
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They don't. It's cobblers. Diesels are worse and you often have to change gear to actually get any increase in speed. The advanced instructor I spent some time with mentioned this and how it was changing police driving as you had to faff about with 1 or even 2 gear changes during overtakes with some cars.
Only diesel I've driven that wasn't a complete pile of excrement was the honda civic 2.2. That accelerates a bit like a petrol but still wheezy at 4k. It mentions 0-60 times comparable to a 1.8 vvti toyota in the toyota celica. I've not driven the toyota so I couldn't compare.
In gear overtaking acceleration is useful to know. Driven used to do it with their car tests. Showed up some wheezy useless less cars for what they were.
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Off the line so to speak diesels lower revving limits require gear changes when the petrol does not. This inevitably will slow it down diesels wrt petrols.
FWIW we run a Fiat 1.9Multijet diesel (150BHP) and an Alfa GTA 3.2v6 petrol (250BHP).
In gear accelerations, again the petrol is better but then its a v6 so not exactly fair comparison..
Both have their good points and bad, but I much prefer the Alfa :)
Last edited by: PR on Thu 10 Mar 11 at 09:51
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My brother's 3.0TDI A5 apparently out-performs its petrol sibling. Having been in it, I'm not inclined to disagree!
I don't think you could tell that my BMW 120d is a diesel just by driving it, though. The autobox disguises the big whack of torque and you can't even hear the engine or turbo even when it's being thrashed.
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The new Jag XJ 3 litre V6 diesel has some astonishing performance figures, comparable to my 4.3 litre V8 petrol.
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Proof is in its power-torque curve.
Physics says more torque means more acceleration.
But again diesel cars are usually heavier.
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>> Proof is in its power-torque curve.
>>
>> Physics says more torque means more acceleration.
>>
>> But again diesel cars are usually heavier.
Comparing engine output torque is a waste of time because, as I keep saying, diesels are higher geared than petrols. You need to be comparing torque at the driving wheels and not everyone has the knowledge to calculate what that is.
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>> The new Jag XJ 3 litre V6 diesel has some astonishing performance figures, comparable to my 4.3 litre V8 petrol.>>
I can vouch for that as I've driven a mate's XJ with this engine - in fact it's a superb car and he rates it even better than his previous S-Class.
But he didn't feel shortchanged when we were out in my Jetta Sports 170 and was, in fact, very impressed with its performance levels.
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L'escargot
I read lots of opinions that diesel cars accelerate faster than petrol cars of similar engine capacity, but nobody ever gives any proof. So ............ here's your chance. Car model, engine capacity and type, acceleration times, and source of information.
Fenlander
tinyurl.com/6h2kvze
L'escargot
Quoted engine output torque perhaps, but the difference in torque at the driving wheels will be reduced by virtue of the higher gearing of the diesel.
Me
Confused. OP asks for "proof". Fenlander provides "proof". OP goes off at a tangent talking about gearing. The link shows two 1.4 hatches, the diesel being quicker. Does this not answer the original request ?
I thought the link ticked all the boxes of the requested information.
Car model: Citroën C3 Hatch
Engine capacity & type: 1397 diesel vs 1360 petrol
Acceleration times: 13.7 diesel 14.2 petrol
Source of information: What Car?
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Or,
Volvo C30
1984 diesel vs 1999 petrol
8.1 vs 8.8 Top speeds 137 vs 130
Source: What Car?
Last edited by: gmac on Thu 10 Mar 11 at 11:49
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I don't give a toss, you lot are arguing about fractions of a second here or there which are not used in everyday driving. I don't partake of traffic light races, and prefer a diesels mid range torque. If I preferred the petrol engines characteristics I would buy one, but I don't.
Last edited by: Old Navy on Thu 10 Mar 11 at 13:16
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Useless comparison.
Compare petrol turbo vs diesel turbo and it's more worthwhile.
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Lygonos, I think you're nearly at the nub of the issue there.
For normal everyday driving a very large capacity engine is nicest to drive.
A smaller turbocharged engine gives many of the same benefits of torque available from lowish revs.
Most people do not wish to pay the fuel costs of a turbo-petrol, although the TSi engines and the like are starting to change that.
Therefore, given the above, the diesel is often the best overall compromise for everyday driving. My view is that, when driving up to about 80% of max, diesel is more relaxed. On a racetrack you'd want petrol, probably. Although, like all generalisations, I bet there are exceptions.
If TD is not to everyone's taste then all the better - variety improves life!
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>> On a racetrack you'd want petrol, probably. Although, like all generalisations, I bet there
>> are exceptions.
Eg. Le Mans - how many years have diesels been winning now?
EDIT: BTW I've never driven more than a couple of miles in a diesel
Last edited by: Focus on Thu 10 Mar 11 at 14:37
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>> Le Mans - how many years have diesels been winning now?
5?
Le Mans isn't to do with acceleration though, Jacky whats-his-name did the standing about until everyone set off then strolled over to his car for a pre-race check then beat everyone to the finish line.
Since the diesels have been winning there's been a fair increase in distance. Same reason petrol's not the right technology for a long haul HGV, diesel's not the right technology for getting a shift on.
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Well you got a few bites, L'es... ;-)
Rather pointless discussion unless you actually narrow down exactly what you are trying to compare... all to vague to give a sensible reply at the moment...
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>> .......... unless you actually narrow down exactly what you are trying to compare...
I thought I'd done that in my original post.
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>> Useless comparison.
>>
>> Compare petrol turbo vs diesel turbo and it's more worthwhile.
Yes, a diesel really needs a turbo to provide any sort of performance - turbocharge a petrol engine and it's bye bye diesel.
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Okay small sample, but very comparable cars BMW E46 3 litre diesel and petrol
0-62 mph diesel 7.2secs petrol 6.5 secs
50-75 (in 4th) diesel 6.1 secs petrol 6.9 secs
Clearly showing... a difference. Personally I like a revvy petrol.
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L'es
You say in the thread on DERV's keeping qualities that you'd never buy a diesel. Fine for you, plenty others find the oil burners mid range pull as good as and in some cases better than petrols.
Excepting ultra high performance diesels I suspect the petrol usually has the edge on 0-60. However, an ordinary 110PS family diesel car (PSA 1.6, VW units etc) is going to be very close to the equivalent petrols 30-50 or 50-70. I cannot prove that but it's borne out by my own experience at at lower power levels in the 90's changing from a BX16RS petrol to a BX19RD. The diesel had more cc but fewer PS; it's flexibility on the road was a revelation.
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>> it's flexibility on the road
See that's the bit i don't follow - to my mind the wide power band of the Petrol means it's the flexible choice.
Is it more about the choice of transmission i.e. instead of using an automatic petrol, you could use a manual diesel. No gear changing required to accomodate large changes in road speed?
Where in a petrol, if you drove it in 3rd all the time, you could manage even larger, rapid changes of roadspeed in one gear, but because we don't cruise in the powerband of the petrol, you need to change your gearing before you're in the rev range where large torque is produced.
The benefit being that once you're in the area of large petrol torque, the engine's doing it at such a work rate that even a diesel with more torque can't match through higher gearing it can afford.
The diesel makes up for not producing much power at it's peak torque by having so much torque. Ultimately though, if you want flexibility, if you want to travel, you need power.
Otherwise we'd have cars with 10L cummins engines* as the performance diesel option.
* Pat probably would have that anyway if it were an option :-)
Last edited by: Skoda on Thu 10 Mar 11 at 18:05
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You pays your money and you takes your choice.
John
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I think the "power band" of a petrol engine is 4000-6000. Below 4000 there isn't a great deal of torque, especially with NA 16 valve engines which seem to be in the majority. So given the power band of a diesel is 2000-4000, a similar range. Turbo petrols like the VW range seem to be pretty good from "range" aspect, but then the piston rings fail:) Most petrol drivers of NA engines never get into the optimal range! As Ford have commented. The accepted test of flexibility of an engine is the top gear 50-70 range. Here, turbo diesels seem to be quite effective. I drive a petrol at the moment, but have driven over 100,000 in turbo-diesels when I had to commute 40 miles each way. They both get you there, but do it in a different manner:)
Last edited by: NortonES2 on Thu 10 Mar 11 at 19:36
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Norton, in your example the diesel wins hands down range wise. 2000-4000 is a much larger range than 4000-6000. It is a 100% increase in road speed, not a 50%.
I think you're wrong actually, I think the range of both types is about equal in terms of road speed increase, but I have lost that argument before.
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>> 4000-6000 ... The difference is most petrol drivers never get into the optimal range
That might possibly be a UK-centred issue.
Early Ford Zetec petrol engines suffered from sticking valves, a problem which affected far more cars in the UK than in continental Europe. It seemed that UK drivers hardly ever revved their engines up to the red line, whereas European drivers were more likely to use the engine's full range on a regular basis.
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Yes, my limited knowledge of German driving (lived there as a child for 4 years) and being passengered on later trips, as well as some driving, they seem to drive to the maximum possible rpm (urban speed limits being observed more or less) as a matter of course. Bears out your comment.
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>> The accepted test of flexibility of an engine is the top gear 50-70 range.
>> Here, turbo diesels seem to be quite effective.
I read a motoring article when diesel engines were first offered in mainstream cars in the UK. The writer was in some petrol hot hatch, following a diesel Honda Accord (IIRC) along a fairly challenging A-road. He said that the Honda slowed down to well below normal speed in the corners, but at every straight stretch of road it just zoomed off into the distance in a way that the hot hatch couldn't match without dropping down a couple of gears.
When he eventually overtook the Honda he was surprised to see it driven by a middle-aged gentleman in a suit who looked like the last person to go racing along an A-road. He drew the conclusion that the Honda driver must have bimbled around in top gear everywhere for the last thirty years, but never before in a car with so much mid-range torque.
Last edited by: Dave_TD {P} on Thu 10 Mar 11 at 19:49
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>> When he eventually overtook the Honda he was surprised to see it driven by a
>> middle-aged gentleman in a suit who looked like the last person to go racing along
>> an A-road. He drew the conclusion that the Honda driver must have bimbled around in
>> top gear everywhere for the last thirty years, but never before in a car with
>> so much mid-range torque.
I remember being behind one of these when they were still relatively new. He pulled away from me pretty effortlessly, now whether he was gunning it or driving in a normal way is up for debate, but I did have to rev the old straight six beemer to keep up. If you read the Honest John test on these, it seems that they are pretty effortless - a combination of good torque and aerodynamics - it's not hard for the car to reach high speeds, and you don't feel them.
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Interesting discussion.
I've never taken too much notice of 0-60 times, those are for people who take Clarksons et al's advice about cars, and talk about brake (bhp apparently, the new god).
'Motor' magazine used to publish in gear acceleration times, though these always favoured proper auto's which would obviously kickdown, they still gave a far better feeling of a cars useable power.
A few have mentioned the fact that those who compare TD with NA petrol are comparing apples and lemons.
I've not driven many petrol turbo's, those that i have driven would leave all but the biggest (German usually) Diesels standing.
It's only anecdotal, but the C2 VTS Diesel we bought was left behind quite easily by the old 3.2 petrol MB, now we've had the C2 a few months and SWM has trained it properly i think the opposite may well be the case (apart from standing starts).
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As I hinted above, I think that the way engines are being compared in this thread is not particularly meaningful.
One more helpful way to remove effects of size is to compare the brake specific fuel consumption of different types of engine - effective how much fuel is burnt per BHP produced.
There's an interesting table on this page, where it's clear that to get below 200 g/kWh, you need to use diesel.
As an aside, there's also an engine performance map shown on this page which shows which part of the engine's operating range gives the best efficiency. It's interesting to note that as most car engines are massivley oversized, we are running them at far too *low* a load for them to be anywhere near their best efficiency.
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>> Otherwise we'd have cars with 10L cummins engines* as the performance diesel option.
>>
>> * Pat probably would have that anyway if it were an option :-)
Have you ever had a drag race with a big engined tractor unit, ie one without its 30 foot of trailer?
They are suprisingly quick.
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>> Have you ever had a drag race with a big engined tractor unit, ie one
>> without its 30 foot of trailer?
>>
>> They are suprisingly quick.
Not a race, but I had one behind me on the A66. Having that beast appearing over the crests and bearing down on me in a Duel-like fashion was quite scary.
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>> >> They are suprisingly quick.
I think pat would want one of these.
www.scania.com/products-services/trucks/truck-range/v8/Engine/730-hp.aspx
Last edited by: Zero on Thu 10 Mar 11 at 20:27
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>> I think pat would want one of these.
That looks pretty decent for a daily driver. I could commute in that.
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>> >> >> They are suprisingly quick.
>>
>> I think pat would want one of these.
>>
>>
>> www.scania.com/products-services/trucks/truck-range/v8/Engine/730-hp.aspx
>>
I recon I could just squeeze one of them in the front of my Ceed. :-)
Don't think my gearbox would last long though.
Petrol, Pah!
Last edited by: Old Navy on Thu 10 Mar 11 at 21:00
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>> L'es
>>
>> You say in the thread on DERV's keeping qualities that you'd never buy a diesel.
>> Fine for you, plenty others find the oil burners mid range pull as good as
>> and in some cases better than petrols.
>>
>> Excepting ultra high performance diesels I suspect the petrol usually has the edge on 0-60.
>> However, an ordinary 110PS family diesel car (PSA 1.6, VW units etc) is going to
>> be very close to the equivalent petrols 30-50 or 50-70. I cannot prove that but
>> it's borne out by my own experience at at lower power levels in the 90's
>> changing from a BX16RS petrol to a BX19RD. The diesel had more cc but fewer
>> PS; it's flexibility on the road was a revelation.
>>
You've proved my point. which is that you've just given your opinion without any figures to back it up.
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There are some (to me) very confused arguments here.
Take a typical naturally aspirated petrol and a typical turbo diesel engine in identical cars, and with identical maximum power outputs (capacity irrelevant, it is what it is).
1. The diesel will be more economical, driven sensibly to the same performance.
2. In the real world, cruising at say half maximum rpm, I would expect the diesel to have better marginal in-gear acceleration owing to being close to, if not at, maximum torque while the petrol would be producing not more more than half its (lower) maximum torque albeit at slightly higher rpm.
Driven to the max, using the gears optimally, they will be very close in performance - but who cares about that 99% of the time?
I don't get excited by my very ordinary diesel CRV, but I do admire the fact that it will do just about anything I want in third from 15mph. It is currently showing 45mpg on the on the cumulative consumption too.
But as somebody said, chacun a son gout.
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Just wait til they start selling/taxing petrol and diesel by the kilo rather than by the litre.
Small petrol turbo all the way.
Says the guy with a 3.2 litre 4 cylinder turbodiseasel... )
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A worthwhile comparison would be something like the VAG 170bhp 2.0 CR TDI and 170 ish BHP 1.4 TFSI.
I suspsect that the TDi would be more economical in real world driving as well as a being a lot more flexible (around 260 lb/ft v 175 lb/ft) despite the TFSi being great for a 1.4 petrol engine in that respect.
I also supsect that the OP is talking about n/a petrol engines, you could add, say, a BMW 2.0 4cyl n/a petrol engine (120i etc) to the above comparison, similar power though less economical than both and less torque, around 155 lb/ft.
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Cheddar there's a £6k price difference in vw golfs with those 2 engines. And the diesel comes with less spec despite the price tag.
Even with the dubious comparability (would someone looking at one also be considering something £6k away in price?) and the significant engine size disadvantage, not to mention the 10ps power disadvantage (1.4 is only in 160ps tune in the golf), even given all that, the diesel is 0.2 seconds faster in the 50-70 in 6th gear.
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>>A worthwhile comparison would be something like the VAG 170bhp 2.0 CR TDI and 170 ish BHP 1.4 TFSI.>>
As I've stated in another thread, my manual 1.4-litre Jetta Sports 170 (168bhp) TSi is only very marginally behind a mate's Jaguar XJ automatic with the three-litre diesel unit performance wise.
However, many people still don't appreciate that driving a diesel means changing up as soon as the revs start to fall off, otherwise you begin to lose the initial momentum, whereas a petrol powered vehicle can be left in gear for at least 2,000-3,000 revs longer.
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>>As I've stated in another thread, my manual 1.4-litre Jetta Sports 170 (168bhp) TSi is only
>> very marginally behind a mate's Jaguar XJ automatic with the three-litre diesel unit
>> performance wise.
Bless ;-)
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One reason diesels can appear to accelerate faster than petrols, is due to the smokescreen they commonly leave behind under hard acceleration........
Another is lack of grip resulting in wheelspin due to spilt diesel on the roads (something I have noticed a lot of since getting back on a motorbike!)
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>>> is due to the smokescreen they commonly leave behind under hard acceleration........
Another is lack of grip resulting in wheelspin due to spilt diesel on the roads (something I have noticed a lot of since getting back on a motorbike!)
Are you in a 1970s parallel universe?
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"Are you in a 1970s parallel universe?"
Probably the same one that L'Esc inhabits where all the fuel stations have separate petrol and diesel pumps, so that he doesn't get his feet dirty!
Actually, I'd quite like that, as then I wouldn't have to breath in all those benzene fumes from the petrol fillers...
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Well I'll stand by what I said earlier:
"Well you got a few bites, L'es... ;-)"
There's plenty of evidence around showing that in equivalent bhp engines the petrol is normally quicker to 60 but the diesel quicker mid-range, try googling it...
All this thread has done is start up yet another petrol vs diesel discussion which has come to the same conclusions as before that some people prefer to rev their engine (petrol likers) and some people prefer an engine where you don't need to have to change all the time (diesel likers)... Ah well, I suppose it was interesting to air the views again! ;-)
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>> Actually, I'd quite like that, as then I wouldn't have to breath in all those
>> benzene fumes from the petrol fillers...
You can't beat the smell of BP Ultimate..
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>>You can't beat the smell of BP Ultimate.>>
...oh I wouldn't like to bet on that...:-)))
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Where in the Uk do you chaps actually accelerate 0 to 60 ? , bearing in mind that I think only myself and Zero and one other actually admitted to speeding.
There must be a lot of sinners here.
There was a good 5th Gear test a while back with Tiff Needel pitting a Mini Cooper against a Skoda Fabia VRS around a track.
Have a guess which one one.
www.youtube.com/watch?v=RUHjV2U3ipA
And again Clarkson v Hammond.
www.youtube.com/watch?v=w8rPhOApnSA
And the diesel will give you many more miles per gallon.
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Cooper = 115hp 1.6 NA petrol
vRS = 130hp 1.9 Turbo diesel
Your point?
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>> bearing in mind that I think only myself and Zero and one other actually admitted to
>> speeding.
>>
>> There must be a lot of sinners here.
I think you'll find, MrT, that most of us have admitted to exceeding the speed limits from time to time if you look back at our post history on here and HJ...
Regards 0-60, I agree, its rather irrelevant on a day to day basis, but they have to include some sorts of comparison, just like mpg figures, that's why some are starting to include 30-50 and 50-70 as being more relevant to daily driving...
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The more relevant 30-50 and 50-70 figures have been included in detailed road tests for yonks! The more abbreviated impressions, in reality regurgitation of press releases, in the ordinary press tend to go for the silly headline 0-60 figure. Force of habit. Saves thinking and write-up time I suppose.
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>> The more relevant 30-50 and 50-70 figures have been included in detailed road tests for
>> yonks!
You are quite right, I just get the impression that only over the past few years have the "ordinary" motoring press (rather than the decent mags!) actually started to use the figures, rather than the 0-60 as their main measurement...
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With you now! I was thinking of the unimproved, syndicated stuff that appears in regional papers, as well as some national.
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>> "Are you in a 1970s parallel universe?"
>>
>> Probably the same one that L'Esc inhabits where all the fuel stations have separate petrol
>> and diesel pumps, so that he doesn't get his feet dirty!
I don't go to the pumps in bare feet.
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>> Are you in a 1970s parallel universe?
>>
No, most definitely in 2010.
In the 70's most diesel engines were in trucks, and they didn't use turbochargers..
There is a lot more spilt diesel on the roads today, than I remember in the 70's and 80's when I did most of my motorcycling.
Last edited by: VxFan on Sat 12 Mar 11 at 00:24
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>> There is a lot more spilt diesel on the roads today, than I remember in
>> the 70's and 80's when I did most of my motorcycling.
>>
Lot more lorries and busses around... as well as the dreaded white vans... I'm not convinced at all that cars are responsible for diesel spills, unless you have evidence?
I can't remember when I last saw a leak from a car fuel tank or filler when out on the road... However I have seen plenty of dirty marks down the sides of said white vans and from the buses which may be to do with this... Though at traffic lights its normally badly maintained engines dropping engine oil than diesel! ;-)
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>>Though at traffic lights its normally badly maintained engines dropping engine oil than
>> diesel! ;-)
>>
Close... its not always engine oil, but leaking high pressure fuel lines dropping diesel over the engine, then onto the road.
You may be surprised how many HP pipes, seals, drive belts, and coolant hoses I sell due to this problem.
I will agree that not many cars loose fuel through the filler cap.
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>>I will agree that not many cars loose fuel through the filler cap.
Probably because they'd fail the MOT:
www.motuk.co.uk/manual_720.htm
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Okay, on my car, the Honda Accord, looking at the 2.0 vtec petrol versus the 2.2 i-CTDi diesel. Figures sourced from autoroadtests.com
Test i-CTDi 2.0
0:60 - 9.6 8.0
30:50 - 3.4 3.6
40:60 - 4.4 3.7
50:70 - 5.3 5.8
Urban 42.2 27.4
Combined 52.3 36.7
So, as we would predict, the diesel is slower 0-60, but has an advantage over the petrol in the midrange other than 40:60. This will be a function of 30-50 being a straight drag in 2nd, and 50-70 ideal range for 3rd (which pulls hard to 85). 40:60 requires a change or starting slightly below the powerband, so the petrol wins.
If I'm honest, the figures are closer than I expected. The figures I can't quite understand are the quarter mile and Km.
Qtr mile 17.5 s/82 mph 16.3 s/88 mph
Km 23.6 s 29.5 s
So the diesel loses over the quarter mile but wins the standing Km.
Anyway, at the very least I think this proves the cars are comparable on paper. The critical difference is the fuel economy is very different. And more subjectively, that sort of pace is harder (in my opinion only) to keep up in the Petrol, hence why I personally paid the premium for the diesel.
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Sorry, the formatting doesn't really survive being posted. I hope you can see what I mean. If not, figures are from here: www.autoroadtests.com/acceleration.php
You can filter for your own car.
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>> The critical difference is the fuel economy is very different. And more subjectively, that sort
>> of pace is harder (in my opinion only) to keep up in the Petrol, hence
>> why I personally paid the premium for the diesel.
My sentiments also.
We have two mk4 Golfs one 130 bhp turbo diesel, one 150 bhp turbo petrol.
The petrol is slightly quicker outright, the diesel is massively quicker anywhere under 3000 RPM.
The petrol does 28-32 mpg
The diesel does 48-52 mpg
No brainer.
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>> Okay, on my car, the Honda Accord, looking at the 2.0 vtec petrol versus the
>> 2.2 i-CTDi diesel. Figures sourced from autoroadtests.com
Like other posts above, I think this misses the relevant point, if not the one raised by the OP.
The acceleration times quoted are through the gears. Where the turbo diesel should score over the more or less equivalent NA petrol is when driving along at maybe 40% of maximum rpm and accelerating to overtake in the same gear.
It's fairly pointless to compare say 30-50 times for cars of equivalent power when they are driven to the maximum - the times will be near as dammit the same, except for variations that say more about the number of gear changes that have to be accommodated or the drag coefficient of the respective cars.
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It's not power that produces instant acceleration but torque and good turbodiesels have plenty of this at low revs. Oh and proof: well Autocar timed an example of my car a Mark 1 Skoda Fabia VRS at about 2.5 secs 20-40 in second and about 5.5secs 50-70 in fourth which are pretty impressive figures. Modern turbo petrols are decent too and have a wider rev range but still feel a bit limp getting into one after my car. The TDI 130
PD was known for quite a brutal unlinear delivery though.
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My Diesel's definitely slower than an equivalent petrol. Right, that's the end of that argument then. Stick to what you prefer!
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Citreon C1
1.0i VT 3d 12.9 s 98 mph 68 bhp
1.4HDi VTR 5d 15.1 s 96 mph 55 bhp
400cc more but slower than the petrol model!
Jaguar X-Type 2.2 Diesel Sovereign 0-60 8.5 seconds
Jaguar x-type 2.1 V6 0-60 8.9 seconds
So the oil burner is quicker and has higher top speed ! petrol 130 Derv 137 !
so in this case the diesel is quicker
ID
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I haven't driven the C1 diesel but I suspect I'd enjoy it more than the petrol. I had a petrol as a courtesy car for a couple of weeks recently and I thought I was rowing it along with gear lever. Horrible car, especially the night it had four people in it.
Of course the diesel could be worse...
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>> 1.4HDi VTR 5d 15.1 s 96 mph 55 bhp
>> 400cc more but slower than the petrol model!
Well done Doc, couldn't for the life of me think of a NA modern Diesel, i forgot that one was still about.
The rest are still trying to compare forced air induction Diesels (2 turbos in some cases) with NA petrols.
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I take a very simple view. We have a petrol and a diesel version of the same car. They're different in some small ways but both perfectly pleasant to drive. I rarely take a stopwatch with me...
:-)
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Diesels accelerate faster than petrols?
I'll believe it when I get burned off at run what ya brung at Santa Pod :)
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Didnt see the Diesel Seat Leon TDI's outdragging the Petrols in the BTCC then?
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Didn't know they did quarter mile runs in BTCC?
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I think the straights at thruxton are longer than a 1/4 mile.
you dont get very far at Santa Pod do you. Why would you want to race over a distance that a runner can do in less than a minute?
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For the same reason a sprinter sprints. To win.
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Where's the proof that diesel cars accelerate .... - Zero
