4-Cylinder Petrol or 6-Cylinder Diesel
Discussion
There are more components to go wrong on a modern diesel than a modern petrol engine, yes? Those additional components are known to cause specific issues in some cars, yes? How anyone can think the chances that a modern diesel is going to be more reliable than a modern petrol is beyond me.
I'm still trying to get my head around the fact that the 328 is a 4.
The problem is residuals and job publics perception that diesel = higher mpg and lower costs.
That's the only figure they see or think about, mpg, so the unenlightened will always prefer a diesel second hand and totally ignore the equivalent petrol..
You see it all the time, people chop in perfectly good 3 year old cars for the same model because the new one does 5mpg more and costs less to tax. The huge elephant in the room that is depreciation gets conveniently forgotten about.
Big petrols will remain unloved because people think they offer poor economy. The fact that they are significantly cheaper to buy in comparison to a like for like diesel means petrol heads get to enjoy creamy sixes and burbley eights for the same overall cost as the bloke over the road in his 520d without the clatter.
If people looked at lifetime costs over car ownership then purchasing decisions may be different.
The problem is residuals and job publics perception that diesel = higher mpg and lower costs.
That's the only figure they see or think about, mpg, so the unenlightened will always prefer a diesel second hand and totally ignore the equivalent petrol..
You see it all the time, people chop in perfectly good 3 year old cars for the same model because the new one does 5mpg more and costs less to tax. The huge elephant in the room that is depreciation gets conveniently forgotten about.
Big petrols will remain unloved because people think they offer poor economy. The fact that they are significantly cheaper to buy in comparison to a like for like diesel means petrol heads get to enjoy creamy sixes and burbley eights for the same overall cost as the bloke over the road in his 520d without the clatter.
If people looked at lifetime costs over car ownership then purchasing decisions may be different.
littleredrooster said:
Tosh. 400,000 miles in 12 years running secondhand DI diesels and I've had none of that. Pug, Citroen, 2 Skodas, BM and Jag all trouble-free; there's tempting fate!
Sorry - just remembered - the Citroen's lift pump lost pressure gradually and cost me £48 for a new one.
Now, the wife's various petrol cars over the same years have been considerably more expensive; coil packs, crank sensors, cam sensors, seized spark plugs...
Diesels have crank and cam sensors too, probably very similar to their petrol equivalents.Sorry - just remembered - the Citroen's lift pump lost pressure gradually and cost me £48 for a new one.
Now, the wife's various petrol cars over the same years have been considerably more expensive; coil packs, crank sensors, cam sensors, seized spark plugs...
One mate with a Mondeo. Four diesel injectors at £500 each. Conversely I know somebody who had to replace an injector on petrol citroen and it was £30 for the part because the pressure and tolerances are much lower.
Another Mondeo - Dual Mass Flywheel £900
Polo, Injector and Loom over £1000
VW Passat turbo system over £1000
Alfa 147 Fuel pump in excess of a thousand.
My Vectra's got an intermittent ECU light where it goes into limp mode and it was in the main dealers for over three hours and they couldn't work it out. I know somebody with an Astra van with exactly the same issue.
A mate with a 100,000 mile 3 series compact (full bmw history) where the swirl flap disintegrated, ruined bores, head, pistons etc. The engine was scrap and the BMW dealers were talking about 6000 to replace it.
Diesels are far more complicated than petrol these days. Yes coil packs fail but they're not that expensive.
If they aren't used on short journeys and get properly warmed up diesels aren't too bad but you to be doing over 20K per year or running a very large car to consider it.
And even if you're saving money you won't enjoy it, I got so fed up with the (reliable) Vectra that I went out and bought a sports car as well. If I'd bought something more enjoyable I'd have saved a lot of money by only needing to run one car.
swirls flags? is that on the 2.0 from 2004 -ish? swirl flaps springs to mind and 6k is made up numbers. If its the engine I'm thinking of, Rover put it in the 75 (minus the swirl flags) and it runs fine.
silly dealers think BMW drivers are made of money clearly and to scrap a 5k car because of that is barmy. Unless you are made of money...
silly dealers think BMW drivers are made of money clearly and to scrap a 5k car because of that is barmy. Unless you are made of money...
The days of petrol being the simple option are pretty much over I fear :-( Bork factor on a 2.0 TSi (brilliant engine) must be pretty high:
- Direct injection so expensive high pressure injectors
- Turbo, albeit without variable geometry like the lower temp diesel turbos, still have ECU controlled waste gate though
- Dual mass flywheel
- Chain driven but with questionable tensioners leading to borkage
- Too clever for its own good single lambda sensor setup with uber pricey catalytic converter
All that said, it's a brilliant engine and the only thing it's missing is a decent soundtrack.
- Direct injection so expensive high pressure injectors
- Turbo, albeit without variable geometry like the lower temp diesel turbos, still have ECU controlled waste gate though
- Dual mass flywheel
- Chain driven but with questionable tensioners leading to borkage
- Too clever for its own good single lambda sensor setup with uber pricey catalytic converter
All that said, it's a brilliant engine and the only thing it's missing is a decent soundtrack.
Oilchange said:
swirls flags? is that on the 2.0 from 2004 -ish? swirl flaps springs to mind and 6k is made up numbers. If its the engine I'm thinking of, Rover put it in the 75 (minus the swirl flags) and it runs fine.
silly dealers think BMW drivers are made of money clearly and to scrap a 5k car because of that is barmy. Unless you are made of money...
Yes flaps, it was about 2 years ago. Do a search, it's a pretty common fault and if they're ingested the damage can be very extensive. Apparently the Mercedes swirl flaps fail too but normally remain inside the inlet manifold so the borkage factor is much less.silly dealers think BMW drivers are made of money clearly and to scrap a 5k car because of that is barmy. Unless you are made of money...
The Rover lacks the variable vane turbo and is regarded as a more reliable car because of it.
The BMW dealer were quoting about £6K for a brand new engine fitted including a grand of VAT. I'd reckon that would be about £2K in labour so £3,000+VAT wouldn't be excessive for a brand new diesel engine. Me and another friend found companies offering to fit second hand engines for about £2,000 but he wouldn't go for it and bought a nearly new petrol Honda Civic instead.
Obviously swirl flap failure is preventable but their removal is another cost that has to be factored into buying the car.
I am considering a new Dacia Diesel on the basis of the 100,000 mile warranty and being prepared to throw the car away at the end of the 7 years as compared with the petrol it would save about £1,000 over that mileage (taking into account the additional purchase price) but can't help thinking there are better options.
Diesel makes sense on really big cars where it's the difference between 25mpg and 35mpg as the percentage improvement is high and the weight of the additional sound insulation is less of an issue but between 40mpg and 50mpg it's more marginal.
va1o said:
I find it a very odd comparison. In terms of price you'd expect a 6-cylinder petrol to cost thereabouts the same as a 4-cylinder diesel on the used market, so I'm not sure why OP has turned it the other way round?
I assume that the discussion concerns the list prices of the respective cars.Fastdruid said:
The torque is great but it's so short a duration that you need to permanently be changing gears if anything other than constant speed cruising is what you want.
please, not this AGAIN!Right, i'll say it again for the benefit of the, er, slower, members:
Petrol 328i - 6 (or 8) gears, goes between 0 and 155mph
Diesel 330d - 6 (or 8) gears, goes between 0 and 155mph
Wow, it must be witchcraft (or the fact that the final drive ratio is the diesel is higher by the same percentage that OmegaMax is lower than the petrol............
For me the choice is easy:
company car? get the diesel
otherwise:
Do short journeys mostly (<15miles say) get the petrol
Do longer journeys mostly (>15miles) get the diesel
There is hardly any difference in costs to run either these days, and both are just as likely to bork themselves (but if your considering buying a new car, you want to be worried about the definite depreciation on a £35k car, rather than the "might happen" breakdown costs
Max_Torque said:
please, not this AGAIN!
Right, i'll say it again for the benefit of the, er, slower, members:
Petrol 328i - 6 (or 8) gears, goes between 0 and 155mph
Diesel 330d - 6 (or 8) gears, goes between 0 and 155mph
Wow, it must be witchcraft (or the fact that the final drive ratio is the diesel is higher by the same percentage that OmegaMax is lower than the petrol............
For me the choice is easy:
company car? get the diesel
otherwise:
Do short journeys mostly (<15miles say) get the petrol
Do longer journeys mostly (>15miles) get the diesel
There is hardly any difference in costs to run either these days, and both are just as likely to bork themselves (but if your considering buying a new car, you want to be worried about the definite depreciation on a £35k car, rather than the "might happen" breakdown costs
Is this a serious post or have I mis-read it (maybe I'm, er, slower)? Are you saying Right, i'll say it again for the benefit of the, er, slower, members:
Petrol 328i - 6 (or 8) gears, goes between 0 and 155mph
Diesel 330d - 6 (or 8) gears, goes between 0 and 155mph
Wow, it must be witchcraft (or the fact that the final drive ratio is the diesel is higher by the same percentage that OmegaMax is lower than the petrol............
For me the choice is easy:
company car? get the diesel
otherwise:
Do short journeys mostly (<15miles say) get the petrol
Do longer journeys mostly (>15miles) get the diesel
There is hardly any difference in costs to run either these days, and both are just as likely to bork themselves (but if your considering buying a new car, you want to be worried about the definite depreciation on a £35k car, rather than the "might happen" breakdown costs
A) you can't tell the difference in "power" delivery (or whatever term you prefer) between a petrol and a diesel engine?
B) you honestly believe the running costs are about the same between the two (maintenance, service and repairs, excluding fuel)?
0a said:
I have been very surprised how unrefined the 7 series and s-class 6 cylinder diesels are - a massive step back from a 6 cylinder petrol, however much we delude ourselves.
Different end of the scale but I found the same with a 12-plate Astra the other day, horribly rough and unrefined. Felt like a step back to the 1990s and not up to the standard of so called modem diesels. That got me thinking is it a result of the ever ridiculous emissions requirements meaning diesels are now going backwards in refinement?
Liquid Tuna said:
Is this a serious post or have I mis-read it (maybe I'm, er, slower)? Are you saying
A) you can't tell the difference in "power" delivery (or whatever term you prefer) between a petrol and a diesel engine?
B) you honestly believe the running costs are about the same between the two (maintenance, service and repairs, excluding fuel)?
Of course you can tell the difference, however the point i am making is that the engine choice in a passenger car has more to do with the distances you regularly drive than any other parameters these days. The fact someone is even considering a diesel says "this is not a sports car" to me, so at that point it's a financial / drivefeel thing. And here's the thing, these days on new cars, fuel choice is getting irrelevant! This is because as quickly as "high rpm diesels" are shifting peak power up the rev range "high torque downspeeded gasoline" engines are moving peak power down the rev range. TDI compression ratios are falling to meet the rising GDI ratio's too, so burn rate (and rate of pressure rise bar/degCA) and hence "combustion noise" are getting very similarA) you can't tell the difference in "power" delivery (or whatever term you prefer) between a petrol and a diesel engine?
B) you honestly believe the running costs are about the same between the two (maintenance, service and repairs, excluding fuel)?
Both are forced induction direct injected, one happens to have spark plugs one has glow plugs!
A modern GDI will be making peak torque flat between about 2k and 4k rpm, with peak power at ~6000rpm.
A modern TDI will be making peak torque flat between about 1k8 and 4krpm, with peak power just under 5k.
Both will be comfortably be producing 30bar BMEP.
Both will be fitted with multispeed transissions.
Both will return very similar economy, although in the real world the lean burn diesel will return an overall better economy.
The diesel will cost more to buy, but will retain a higher % of it's cost over time
The gasoline will have a better NVH from outside, but from the cabin there will be very very little to seperate them (and if we are talking 6cyl TDI vs 4cyl gasoline, the diesel will actually be better!
Neither will be cars that you would go and drive "just for the fun of it"........
CDP said:
Diesels have crank and cam sensors too, probably very similar to their petrol equivalents.
One mate with a Mondeo. Four diesel injectors at £500 each. Conversely I know somebody who had to replace an injector on petrol citroen and it was £30 for the part because the pressure and tolerances are much lower.
Another Mondeo - Dual Mass Flywheel £900
Polo, Injector and Loom over £1000
VW Passat turbo system over £1000
Alfa 147 Fuel pump in excess of a thousand.
My Vectra's got an intermittent ECU light where it goes into limp mode and it was in the main dealers for over three hours and they couldn't work it out. I know somebody with an Astra van with exactly the same issue.
A mate with a 100,000 mile 3 series compact (full bmw history) where the swirl flap disintegrated, ruined bores, head, pistons etc. The engine was scrap and the BMW dealers were talking about 6000 to replace it.
Diesels are far more complicated than petrol these days. Yes coil packs fail but they're not that expensive.
If they aren't used on short journeys and get properly warmed up diesels aren't too bad but you to be doing over 20K per year or running a very large car to consider it.
And even if you're saving money you won't enjoy it, I got so fed up with the (reliable) Vectra that I went out and bought a sports car as well. If I'd bought something more enjoyable I'd have saved a lot of money by only needing to run one car.
Petrols are going the same way as dieselsOne mate with a Mondeo. Four diesel injectors at £500 each. Conversely I know somebody who had to replace an injector on petrol citroen and it was £30 for the part because the pressure and tolerances are much lower.
Another Mondeo - Dual Mass Flywheel £900
Polo, Injector and Loom over £1000
VW Passat turbo system over £1000
Alfa 147 Fuel pump in excess of a thousand.
My Vectra's got an intermittent ECU light where it goes into limp mode and it was in the main dealers for over three hours and they couldn't work it out. I know somebody with an Astra van with exactly the same issue.
A mate with a 100,000 mile 3 series compact (full bmw history) where the swirl flap disintegrated, ruined bores, head, pistons etc. The engine was scrap and the BMW dealers were talking about 6000 to replace it.
Diesels are far more complicated than petrol these days. Yes coil packs fail but they're not that expensive.
If they aren't used on short journeys and get properly warmed up diesels aren't too bad but you to be doing over 20K per year or running a very large car to consider it.
And even if you're saving money you won't enjoy it, I got so fed up with the (reliable) Vectra that I went out and bought a sports car as well. If I'd bought something more enjoyable I'd have saved a lot of money by only needing to run one car.
Higher injection pressure
Turbos
Higher compression
GPFs
Swirl and tumble devices in the intake to help with reducing cold start particulates
List goes on. Petrol and diesel are converging.
I recently changed from a 2.0 TFSI (Mk5 GTI) to an (X3) 30D. Loved the TFSI, but it did sound a bit like a diesel at low revs and started to run out of ideas around 6,000rpm. It also specified 98 RON, which works out more expensive than diesel at most pumps.
OTOH the BMW 30D seems quite refined with its 6 cylinders -- definitely still sounds like a diesel, but certainly quieter and less of the 'dag-dag-dag' that you get with the 4-cylinder units. Performance and economy are exceptional. Rather laggy (in non-sport), but you get brutal power when the boost kicks in.
Overall, in a big(ish) car, I'd pick a 6-cylinder (BMW) diesel over any 4-cylinder petrol unit.
OTOH the BMW 30D seems quite refined with its 6 cylinders -- definitely still sounds like a diesel, but certainly quieter and less of the 'dag-dag-dag' that you get with the 4-cylinder units. Performance and economy are exceptional. Rather laggy (in non-sport), but you get brutal power when the boost kicks in.
Overall, in a big(ish) car, I'd pick a 6-cylinder (BMW) diesel over any 4-cylinder petrol unit.
Edited by swamp on Saturday 27th April 22:54
CDP said:
surveyor said:
Fort Jefferson said:
Unless you're buying a new car with a warranty, get a petrol. The cost of making diesels go fast is obscene.
I'm in a bad mood, so please allow for directness.Complete and utter cock.
DMF - what £900?
DPF
Fuel pump at £1500
BMW Swirl flags (quote of £6K on a £5K BMW - needless to say it was scrapped)
Turbos
Everybody I know running a modern diesel has had issues of this sort. The economics just aren't stacked in their favour these days.
Apparently the later BMW 530 petrol can easily beat 30mpg and is officially 37 combined which can't be a lot worse than the diesel.
Modern Petrol engines are becoming just as complicated as diesels with Turbo's etc.
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