Long commute...

[Lewis_RX8]

@cardiffrob Area you any closer to a decision after all this?

Yup look @Wildefalcon has picked out all the good traits of cars after input from the forum , Just needs a bit of welding to combine them all in the perfect long commute high comfort cruiser

And so the conclusion:

OP needs a VW group car with a Volvo seat and a V8.

 

[Fastdruid]

Care to back that up then?

Yep.

Firstly you are largely comparing implementations rather than inherent. Inherently NA petrols have a higher BMEP (which can be used to compare engines regardless of capacity or type) than NA diesels. Of course when you increase the boost you up the effective capacity and with a diesel there is also very little downside to increasing boost (and many upsides, including making economy *better*) which has the effective result of increasing the torque.

Diesels also *HAVE* to make more torque because they can't rev due to a number of issues, primarily for road cars it's timing issues (as the window for injection is vanishingly small) and also because the cylinder pressures are higher the crank, piston etc have to be heavier which also limits speed and at the same time allows more torque. So making their torque at the lower end is a *choice* in implementation to get power. Primarily diesels are also helped through being longer stroke vs their petrol counterparts. Again this is a *choice* rather than inherent but as longer stroke means more torque (at the expense of less power and ability to rev) they generally are designed that way.

In that respect "diesels have more torque" is correct, in the majority of implementations they do.

But that then brings us to the second point, gearing. The crankshaft torque is an irrelevance when they have to be massively up geared to have any rev range. Yes, many diesels will make lots of torque in 1st gear but a petrol engine in an equivalent state of tune will make more power and more torque at the wheels because it can run 1-2 gears lower than the diesel (for example at maximum torque it may still be in 2nd while the diesel is in 4th).

So yes, many diesels will have massive figures at the crankshaft for playing pub top trumps with, but by the time it's got to the wheels it's all evaporated through the magic of gearing hence it's a popular misconception that they *actually* have more torque.

 

[cardiffrob]

Had a look at a Diesel Golf Estate and a Petrol Fiesta. Both under £3k. Still undecided so I'm still browsing the adverts.

 

[Munkul]

A luxury car with a diesel engine is an oxymoron.

The *only* thing that diesels do better is economy. *Everything* else is better with a petrol engine.

yawn. Same old tired saying by a self-identifying "petrolhead". Have you owned one?

A modern luxury car with a 6 pot, you can barely hear the engine.

A sports car, definitely.

A super luxury car (RR, Bentley etc) sure.

But a "decent" big car - BMW, Audi, Jaguar etc, the sort of thing that most people can actually afford to run on big miles - diesel makes far more sense.

The TDV6 in my XF S is one of the finest engines I've owned (and I've had plenty of sporty cars before as well, so I think I know my own mind)
In fact, the XF S is the best all-round car I've ever owned... the previous XF V8 was a close second though!

 

[Munkul]

Yep.

Firstly you are largely comparing implementations rather than inherent. Inherently NA petrols have a higher BMEP (which can be used to compare engines regardless of capacity or type) than NA diesels. Of course when you increase the boost you up the effective capacity and with a diesel there is also very little downside to increasing boost (and many upsides, including making economy *better*) which has the effective result of increasing the torque.

Diesels also *HAVE* to make more torque because they can't rev due to a number of issues, primarily for road cars it's timing issues (as the window for injection is vanishingly small) and also because the cylinder pressures are higher the crank, piston etc have to be heavier which also limits speed and at the same time allows more torque. So making their torque at the lower end is a *choice* in implementation to get power. Primarily diesels are also helped through being longer stroke vs their petrol counterparts. Again this is a *choice* rather than inherent but as longer stroke means more torque (at the expense of less power and ability to rev) they generally are designed that way.

In that respect "diesels have more torque" is correct, in the majority of implementations they do.

But that then brings us to the second point, gearing. The crankshaft torque is an irrelevance when they have to be massively up geared to have any rev range. Yes, many diesels will make lots of torque in 1st gear but a petrol engine in an equivalent state of tune will make more power and more torque at the wheels because it can run 1-2 gears lower than the diesel (for example at maximum torque it may still be in 2nd while the diesel is in 4th).

So yes, many diesels will have massive figures at the crankshaft for playing pub top trumps with, but by the time it's got to the wheels it's all evaporated through the magic of gearing hence it's a popular misconception that they *actually* have more torque.

IMHO you need to think a little more simplistically...
You can't compare engine size/specific output - petrol will always have a higher specific output like you say, and fair enough.
but, we're comparing outputs... ie a 250hp diesel vs a 250hp petrol. Say both turbocharged, but one is probably a 3.0 and the other a 2.0, which is reasonably commonplace.
It's not about the peak figures, not even about peak torque per se, it's about area under the curve.
Output for output, a diesel will have a shorter curve (because they rev less) but a fatter curve, with more area than a petrol.
Forget gearing entirely - you have to assume it's correct for the engine's torque characteristics.
That, coupled with correct gearing, directly translates into superb in-gear acceleration. At cruising revs, you have more instant grunt available. You have to drop a gear or two to overtake with a similar petrol engine. Both will get the job done, but one is a little bit easier.
Diesels are pretty useless in 1st gear in most cars, because the torque is either far too great for the wheelspeed/available grip, or it doesn't get enough time to spool the turbo fully. Most diesels won't even make peak boost until 3rd gear.
But once moving, they're pretty easy to drive fast.
You know what else has a very short and fat torque curve? Rally cars... the throttle restrictor means ultimate air flowrates are restricted, so they tweak the cams and turbo to give as wide and fat a power band as possible. The top end revs tail off in power.

Anyway my overall point is, just because you think something is bad, doesn't mean it is

 

[sako243]

Yep.

Firstly you are largely comparing implementations rather than inherent. Inherently NA petrols have a higher BMEP (which can be used to compare engines regardless of capacity or type) than NA diesels. Of course when you increase the boost you up the effective capacity and with a diesel there is also very little downside to increasing boost (and many upsides, including making economy *better*) which has the effective result of increasing the torque.

Diesels also *HAVE* to make more torque because they can't rev due to a number of issues, primarily for road cars it's timing issues (as the window for injection is vanishingly small) and also because the cylinder pressures are higher the crank, piston etc have to be heavier which also limits speed and at the same time allows more torque. So making their torque at the lower end is a *choice* in implementation to get power. Primarily diesels are also helped through being longer stroke vs their petrol counterparts. Again this is a *choice* rather than inherent but as longer stroke means more torque (at the expense of less power and ability to rev) they generally are designed that way.

In that respect "diesels have more torque" is correct, in the majority of implementations they do.

But that then brings us to the second point, gearing. The crankshaft torque is an irrelevance when they have to be massively up geared to have any rev range. Yes, many diesels will make lots of torque in 1st gear but a petrol engine in an equivalent state of tune will make more power and more torque at the wheels because it can run 1-2 gears lower than the diesel (for example at maximum torque it may still be in 2nd while the diesel is in 4th).

So yes, many diesels will have massive figures at the crankshaft for playing pub top trumps with, but by the time it's got to the wheels it's all evaporated through the magic of gearing hence it's a popular misconception that they *actually* have more torque.

Thanks for some explanation. If I've interpreted it correctly (and I'm willing to be proven wrong) then what you're saying is that if you build an identical diesel and petrol engine then the petrol will be more torquey. Well fair enough and how utterly moronic. Each engine is designed to the characteristics of its fuel.

 

[Pigeon_Droppings2]

I always thought the extra torque was simply down to how the fuel burns Vs combusts in the engine...is that by design or an inherent property of the fuel?...I have no idea...am sure 4 hours of googling would answer the question though!

Maybe it's as simple as working out which fuel has the most energy per volume...and how quickly that energy can be released creating.

 

[sako243]

Torque tends to be produced by longer strokes. Diesels tend to have longer strokes because of the way that the fuel combust (I.e. under compression rather than ignition) hence the stricter timing requirements on fueling.

The longer stroke also tends to limit high rpm because there's more rotating mass.

 

[reb78]

We had a BMW 1 series for a few years. Lovely quick car. 180D - it revved like a petrol - much higher than any other diesel I have driven.

 

[reb78]

Had a look at a Diesel Golf Estate and a Petrol Fiesta. Both under £3k. Still undecided so I'm still browsing the adverts.

Go for the Golf for the 500 mile journey. The fiesta would be fine for local pootling about and an occasional long trip but it will soon get tiresome driving that little thing all that distance.

 

[bigegg]

Had a look at a Diesel Golf Estate and a Petrol Fiesta. Both under £3k. Still undecided so I'm still browsing the adverts.

Go for the golf:
It's an estate, so longer wheelbase = more comfortable (might be negligible).
Diseasel so (probably) cheaper on fuel.
Plus it's not a ford. (I only know about older fiestas, but based on that, it will have rusted away after a 500 mile commute)

 

[Fastdruid]

yawn. Same old tired saying by a self-identifying "petrolhead". Have you owned one?

Why on earth would I want to own one? I've driven plenty of diesels and find them hateful. Just all round deeply unpleasant to drive. I'd rather pay more to not suffer a diesel.

 

[bigegg]

Why on earth would I want to own one? I've driven plenty of diesels and find them hateful. Just all round deeply unpleasant to drive. I'd rather pay more to not suffer a diesel.

Sis has an Audi q5(?) 2.0 diseasel.
It's actually not that bad, tbh.
It *did* cost her 20 grand, second hand, however

I don't think I've spent 20k in total since I started driving in 1998.

 

[Munkul]

Why on earth would I want to own one? I've driven plenty of diesels and find them hateful. Just all round deeply unpleasant to drive. I'd rather pay more to not suffer a diesel.

Your definition of "deeply unpleasant" is different to most people's, then by all means I'm not saying your opinion is wrong, just saying that it's not necessarily an opinion shared by others.

To my mind, a big diesel with an 8spd ZF box makes for the most relaxed motoring you can have.
I will happily w*nk on about how good the current crop of autos are, the 8spd ZF is one of the best transmissions ever made and I've had 3 now - one in a BMW, one in a VW, and one in a Jaguar

I'd happily trade the TDV6 for another 4.2 or 5.0 V8, mind... IF fuel cost wasn't an issue. As it stands, I'll probably go back to a noisy 4 pot 2.0 diseasel next... £90/week in fuel tends to focus the mind on economy!

 

[Fastdruid]

Had a look at a Diesel Golf Estate and a Petrol Fiesta. Both under £3k. Still undecided so I'm still browsing the adverts.

Golf is a different class to the Fiesta. Equivalent Ford to the Golf would be a Focus.

FWIW I've driven both Fiesta (Mk6 1.0T/125PS ) and the Golf (Mk7 R and Mk6 1.6TDI) and the Fiesta was by far more enjoyable to drive but is smaller and given the distances involved and presumably the amount of motorway, unless you're doing it through the twisty depths of Wales/Scotland I'd go for the larger car over enjoyment to drive. I've done long distances in small cars and it's totally doable *but* is far nicer in a larger "cruiser".

Of course depends on year and can't comment on how rusty either are likely to be at that end of the scale.

 

[DAPPH]

Really depends what you want and your budget.

I've just done 1,830 miles in 2 days in my diesel A6, totally comfortable and it did ~42mpg mostly doing 80mph on cruise. No car i'd rather have, the thing eats up the miles.



I had a 54-plate MK4 1.9 estate. Brilliant car, did 60mpg on the motorway, totally reliable.

How many gallons of engine oil did it us in that time ?

 

[DAPPH]

At 250 mile each way trip I'd go for a big high end diesel auto 7 or 8 speed box that gives 50 or more mpg . After a while sitting with your knees up by your chest on a regular basis makes having a small higher mpg car feel a bit of a bad decision .

 

[DAPPH]

Avoid french.

Im quite impressed by our Kia's from a maintence perspective.

Surprised you say that KRAM , all four of our Citroen BX's were fantastic on fuel , my BX19GTI was an absolute dream to drive in total comfort , we sold it just after it had gone the third time round the clock .

 

[Justme]

Some of the 4 door pickups fit i to this catergory too, something to do with weight.

Almost none now class as cars with higher limits as they are over 2040kg unladen.

 

[8ob]

Nope. Popular misconception.

Beg to differ, 400hp of petrol car engine is ultimately the same as 400hp of a truck diesel. the max torque or turning forces of most diesels are produced at a very useable and leisurely sub 2000rpm and will go on for a million plus miles. For a petrol engine to compete or produce those max turning forces it would be on the redline, the diesel will live like this forever while the petrol would be on a recovery truck before the end of the first day. Max torque and where in the rev range it’s produced trumps hp figures. Does here anyway.


Bob