What's the appeal of diesel?

[HDi fun]

A question posed by myself, I want to know what the appeal of diesel really is.

Is it the fuel economy? If so, does it really make much sense with the price premium for both the car and the fuel price differential?

It's probably fair to say that you can no longer compare performance or specific output any longer. By which I mean that a 2.0 diesel model will flatten an equivalent 2.0 petrol model from the same manufacturer's range. But the diesel model will cost far more to buy and the running costs will probably still be in favour of the petrol car, unless you cover, let's say, 90,000 miles in three years. Whereupon it's probably a close call.

Performance? Would you buy a petrol car over a diesel just, and only for the performance edge? I wouldn't do that either. But does the petrol have the edge? Litre for litre of engine swept volume, no. But large engine petrol cars are bargains of the century at the moment. No-one want's 'em. So go and drive away in your 3.2 V6 knowing that petrol is only 90.0p/litre and that servicing is 30,000 miles! It reasonable that a 2.2 diesel will stay with it in peroformance wise, but at what cost?

Or do we get carried away with the diesel muscle thing? That massive torque at low-mid revs is addictive. It'll fling you into your seat and fling the car foward in a savage way, tyres squealing, even in third. Until, of course, you have to change up a gear. And you'll be doing that not much after 4000rpm. Even the revvy ones won't go much over 5000rpm but there's no point hanging on to lower gears whatsoever to 5k.

Pitch 200bhp diesel against an equivalent 200bhp petrol model. The diesel will always feel faster in any gear because of the ridiculous torque on offer. The petrol car will feel far more sensible because there's not the massive torque peak of the diesel but it can hang on to second gear until well over 70mph.

It's a close call

Thoughts please,

rgds,

Paul.

[turbonutter69]

Petrol.

[HDi fun]

Originally Posted by turbonutter69

Petrol.

yeah

[turbonutter69]

Me personally prefer the long rev range that a petrol offers. In all honesty I can't see why anyone would pick diesel over petrol. In the long run a diesel will cost more to run than a petrol.

[HDi fun]

Sadly I think all motoring is too expensive.

[turbonutter69]

Not all the time. My Focus is very good on petrol for instance.

[HDi fun]

Diesel does have an appeal. Go and drive a Jaguar XK8 or other similar large engined (3.5 - 4 litre) petrol car. Effortless drive. Now look at the torque figure. The big attraction diesel has is that enormous mid range pull. And that's the kind of driving feel you get with a well set up turbo diesel.

Those of us that drive the things aren't all resigned to a life of 25 second 0-60 times any more and flat out at 75. Trust me, if that were the case I would not go near a diesel car. Much to everyone's opinion I'm nowhere near as much of a dieselhead as you all think. I hated the things for years.

What I have always liked is effortless acceleration - and if I had the cash to run it I might well go for a V8 petrol car. Since I can't the next best thing is a turbodiesel.

[MasterAuron]

Originally Posted by HDi fun

By which I mean that a 2.0 diesel model will flatten an equivalent 2.0 petrol model from the same manufacturer's range.

That massive torque at low-mid revs is addictive. It'll fling you into your seat and fling the car foward in a savage way, tyres squealing, even in third.

massive torque peak of the diesel

Let's make someting clear, you are referring to TURBO diesel here. (An N/A diesel wil never touch it's N/A petrol equivelent). In which case, you'd have to compare it to a turbocharged petrol, which will also have a big peak of torque, but a larger rev range to properly exploit it. From a pure performance point of view it's a no-brainer for me.

However, generally speaking diesel engines tend to be more hard-wearing and imo they are the perfect compromise between economy and performance as to get diesel-matching economy from a petrol engine it will often have to be small displacement and low powered. As an everyday car modern turbo-diesels are unbeatable imo. I'm after one to replace my run-around soon.

[HDi fun]

Absolutely - NA diesels are a waste of time. We've got one here - Seat Ibiza D. 1896cc of raw muscle, all 74bhp of it.

Diesels will always win the torque competition due to very high cylinder BMEPs. And they will generally lose the bhp one due to low rev limits.

It really comes down to personal preference now and nothing else really.

I do like the massive midband torque of my diesel but I have to admit that it's nice once in a while to drive a high revving V6 petrol and just hang onto the gears until 7000rpm plus. Probably not as quick as the Pug but it's fun all the same.

What diesels DON'T like is very low revs, despite what some seem to think. Not many will stand 5th gear at 30mph but most petrols will.

Both have their respectoive places, you pays yer money etc etc.

[waynne]

For me the appeal of the diesel has to be the stealth or hidden power. Its jolly nice having all that Torque on tap. Its a shame that diesel engines don't sound sporty though as this would really add to the appeal.

Diesels are the sensible choice but petrols remain for me the fun choice and give a better driver experience.

[HDi fun]

It's a different driving experience, not necessarily better or worse.

I agree with the sound thing totally. Diesels are very quiet now, especially inside the car but what little noise exists is not at all invigorating. Kind of like a cement mixer that's been wired up to an overhead power line and is doing about 25,000rpm

[waynne]

I can't say I've ever wired up a cement mixer to an overhead power line. Is that why builders charge so much!

[HDi fun]

I haven't done so, either. I suppose it would bring a whole new dimension to the Readymix brand

Now there's a marketing ploy, not for diesel motoring, but for the construction industry.

[RobBentley]

I like Petrol and Diesel for different reasons. The Diesel noise and the type of power 'pulling/torque' suits my Land Rover... where as the revvy nature of a 4.0 petrol suits my Passat.

Diesel is particularly good in off-road situations where alot of revs to get enough 'torque' to move can cause wheel spin - whereas being able to ease massive amounts of torque in from 1750rpm to creep over things is perfect.

[HDi fun]

That also is a good analogy. This is the reason that a diesel with 200bhp feels like a 300bhp petrol engine in the middle of the rev range (1500-4500 say). It's because the torque outputs are similar. Conversely a 200bhp petrol will feel spineless compared to a 200bhp diesel in general driving.

[RobBentley]

Yup - The human body doesn't feel acceleration, it feels torque as its the twisting force driving you forwards. I've seen this before where one car (massive torque) feels very fast because of the twisting force (torque) - and another which is actually much faster doesn't feel as fast.

[HDi fun]

It is torque that causes acceleration. All that happens is the wheels converrt a rotating force into a linear one.

What the human body cannot detect (apart from visually) is steady state speed.

[RobBentley]

Originally Posted by HDi fun

It is torque that causes acceleration. All that happens is the wheels converrt a rotating force into a linear one.

What the human body cannot detect (apart from visually) is steady state speed.

Sorry - I shouldn't type when i've only just woken up!

What I mean't was the body doesn't dectect HORSEPOWER... it detects Torque. Hence a high-torque vehicle can feel faster even if its not.

[HDi fun]

OK, with you now mate. HAving more torque will always shove a car foward more vigorously. What limits diesel engine outputs is lack of revs. Thus a petrol car can use lower gears than a diesel which means there's more torque multiplication to the wheels, which closes the gap between petrol and diesel cars. This is something that's often overlooked. Magazine writers are the worst for this, especially those that think diesel is the be all and end all. Which, you'll be surprised to here me say, it isn't.

[RobBentley]

Indeed. Good example here is my fathers FreeLander TD4 2.2 which pushes 160BHP and 400Nm of torque. From a standstill to 35mph ish it feels notably quicker than my girlfriends 170BHP 2.3 V5 Bora with 220Nm of torque. We know for a fact though - side by side acceleration - the Bora is actually quicker.

[HDi fun]

There are all kinds of comparisons. One of the intersting ones was when we put my remapped 406 with 192bhp side by side (from a standstill) against a V6 Coupe with 211bhp.

They were literally side by side all the way to 60, at which point the diesel started to edge slightly ahead and remained there (only 1/2 car length or so) We aborted at 100mph for safety reasons.

I suspect that once I'd been forced into 5th gear (rev limit 5300, which is unusually high for a diesel) the petrol would have closed with a decisive win.

[RobBentley]

Which brings me to another thing. My sisters 206 2.0 HDi is pretty damn nippy!

[HDi fun]

The fact is this. If it feels quicker then it IS quicker.

But only at that point in time.

Let me explain. A 200bhp diesel will savage a 200bhp petrol car in the 30-60 in third gear test, for example. But, the petrol car will probably be able to do the same 30-60 in 2ND gear, which might well see it quicker than the diesel.

The diesel driver does not have this option as he'd never get to 60mph in second.

What grabs a lot of people the first time the drive a muscular diesel (and I mean 300+ lbft type, not a 12 year old Mondeo one with about 120lbft) is the sheer muscle in the gears. But you have to get through 'em otherwise you're not getting the benefit of all that torque.

This, contrary to popular opinion can actually make a manual diesel LESS relaxing to drive than a similarly powered petrol car.

[weetank]

Basically i think its the torque that provokes people to go for a diesel car. It has to be turbo tho , aint no good without a turbo lol i know alot of people that prefer diesel cause its alot cheaper to run, most of them are farmers and run there d turbos and 1.7td cavs on the red juice puffing out nothing but black smoke. They also like to screw out there pumps and turbos for that bit more power and in all fairness they quite a bit quicker than the 1.2 an 1.4 corsas that go bout my town. But personally id go for petrol far quicker off the line , always have to wait for the big ass turbo in my 1.9 tdi golf to kick in to get some power, the lag is unreal! i have a 60 bhp renault 5 that will eat the pants off it up til bout fifty mph then the torque finally kicks in and the golf would fly by lol

[HDi fun]

I can manage 0-62mph in under eight seconds without going berserk with the clutch so I don't entirely agree about the lag problem.