Diesel or Petrol?

Scania said:
Thanks for that, well explained. :)

I would love to see the results of a project car designed as you describe, I wonder if it's been done by anybody yet? - off to Google I go!

In the mean time, I'll carry on being very non scientific! :o
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Yeah it would be pretty interesting if so.
 
RedvGreen said:
I think Diesels still take a while to accrue their purchase price back if you end up owning it for the full length of the contract; on lease hire though it is negligible.

Diesels offer awesome performance though which not many people actually realise - check out the BMW 335d which can do 0-60 in 4.8secs; the 335i can only do it in 5.2secs.
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Where did you get that figure from? Everywhere seems to quote 6.1/6.2?
 
Janesy B said:
Where did you get that figure from?
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Which figure? There are two. In any case, check here: BMW.

The 335d isn't available in anything but xDrive, likewise the 335i doesn't have xDrive.
It is a fair comparison as the xD system has additional weight, yet generates far more torque (so needs the additional AWD grip). Yet the 335i generates less torque, but is lighter.

Both are 3L turbo engines - One Diesel; One Petrol. Just like the question of the topic asks.
 
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Diesel one might have a DPF which might need changing, thats £1k right there...all your saving gone on one component.
 
RedvGreen said:
Which figure? There are two. In any case, check here: BMW.

The 335d isn't available in anything but xDrive, likewise the 335i doesn't have xDrive.
It is a fair comparison as the xD system has additional weight, yet generates far more torque (so needs the additional AWD grip). Yet the 335i generates less torque, but is lighter.

Both are 3L turbo engines - One Diesel; One Petrol. Just like the question of the topic asks.
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It is not a fair comparison to compare the 0-62 times of 300+ HP RWD and AWD cars. The 335d doesn't have AWD because it 'needs' the grip.

Whether or not a 335d is faster than a 335i cannot be argued from that standpoint - even if it's true.
 
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RedvGreen said:
Which figure? There are two. In any case, check here: BMW.

The 335d isn't available in anything but xDrive, likewise the 335i doesn't have xDrive.
It is a fair comparison as the xD system has additional weight, yet generates far more torque (so needs the additional AWD grip). Yet the 335i generates less torque, but is lighter.

Both are 3L turbo engines - One Diesel; One Petrol. Just like the question of the topic asks.
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I was looking at E90 cars, that'll explain. It's not a fair comparison at all.
 
OK, the 335d/i was the range I am most familiar with, so since you deem that comparison to be unfair, i've had to explore the BMW range. This proved tricky as the N57 engines do not marry up the N55 engines due to AWD vs. RWD being a common issue across the range (it seems BMW doesn't want a fair comparison between the two).

My point was that a diesel engine of certain size will outperform a petrol engine (providing decent engineering has gone into the engines). So for cost, a diesel should also provide better economy as well as performance. What is not to like?

BMW X6 50i vs. X6 50d = Diesel is faster by 0.1sec and way more economical.

Things get a little crazier when you compare the M-range with the big performance diesel engines.

335d and 435d is faster than the 1M, which uses the old N54 twin turbo engine, heavily tuned (not to it's limits though). Tuning the N57 yields yet even more insanity, capable of returning 4.5secs 0-60 and lower still with proper tunes (instead of the Burgertuning kits).

Couple this knowledge with the fact that these big BMW diesels sound fantastic despite being a diesel, and you have more performance, more MPG, decent sound and no drawbacks? (unless you hate buying new tyres - but any big engined BMW will suffer there!).
 
Why explore the other range? You could have just compared the 335d AWD with the 335i AWD!

It isn't the case that typically a diesel engine of a certain size will outperform a petrol engine of the same size - of similar power output, yes, but size is too broad a criteria. BMW is a rare exception, where the x35d is particularly powerful, and the x35i in 306 HP form has been at that power level for 6 years.
RedvGreen said:
Couple this knowledge with the fact that these big BMW diesels sound fantastic despite being a diesel
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Under full load they don't sound bad, but on idle and slow mooching around even the very latest ones are a bit rough.
 
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Given you have competitors like Mercedes producing 360BHP from a 2.0T and VAG with 300BHP 2.0T cars, along with historic engines like the Evo with up to 400BHP from a 2.0T, it would be naive to think the 3.0T 335i is anywhere near 'peak performance'. It has a huge amount of potential to unlock, however it would serve BMW no purpose to do so as they'd hugely infringe on the proper M cars.
 
PMKeates said:
Why explore the other range? You could have just compared the 335d AWD with the 335i AWD!

It isn't the case that typically a diesel engine of a certain size will outperform a petrol engine of the same size - of similar power output, yes, but size is too broad a criteria. BMW is a rare exception, where the x35d is particularly powerful, and the x35i in 306 HP form has been at that power level for 6 years.Under full load they don't sound bad, but on idle and slow mooching around even the very latest ones are a bit rough.
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Umm, the xD 335i doesn't exist on the website to compare stats!
 
RedvGreen said:
We're counting across the seas?!

OK, BMW USA quote 335i xDrive as 5.0secs 0-60 and 335d xDrive as 4.8secs 0-60. (both autos).

Diesel > Petrol... satisfied!!?!
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Not really M8


I don't know how you can base your entire statement on 0-60 times when many people would buy the petrol even if it was 0.1s slower to 60. How many people can really tell the difference between .2 of a second anyway?!
 
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Janesy B said:
Not really M8


I don't know how you can base your entire statement on 0-60 times when many people would buy the petrol even if it was 0.1s slower to 60. How many people can really tell the difference between .2 of a second anyway?!
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0.1 or 0.2 is meaningless unless you're a stats junkie. The real issue is the same performance for greater MPG. Albeit, that performance will be delivered in a fairly linear fashion, akin to the electric sports cars.

Too many people discount diesels thinking they're slow and inferior, they are so wrong (and i've owned an N55 335i too, so fairly well-driven in these two).
 
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