Stuck between engines
Discussion
Have mostly driven 3 litre diesels for the past decade and been quite happy but with rising fuel costs and a new purchase on the horizon I’m beginning to consider a 2 litre instead which seem to be maybe 25% more efficient and the up front cost an also be significantly cheaper too.
As always there are stories of noise and lack of power for the smaller engine but I’m wondering real world for those who have done this, what is it like to live with on a daily basis?
As always there are stories of noise and lack of power for the smaller engine but I’m wondering real world for those who have done this, what is it like to live with on a daily basis?
Having done this myself I'd say yes they're a bit more noisy not overly so (Mondeo Vignale 210) but noticeable I went for a 210 so the loss of performance wasn't too noticeable.
I lasted three months before getting it mapped, in the real world I'd say I'm getting an extra 100-120 per tank vs the 350cdi it replaced but that wasn't mapped, so not an exact apples with apples comparison. My 320cdi was only 80 miles worse per tank than the Mondeo.
Now one thing with the 2.0d's is that you notice the way they're not quite always on the torque in the same way as the 3.0d's are.
My next diesel will be a 3.0d hybrid.
I hope that helps.
I lasted three months before getting it mapped, in the real world I'd say I'm getting an extra 100-120 per tank vs the 350cdi it replaced but that wasn't mapped, so not an exact apples with apples comparison. My 320cdi was only 80 miles worse per tank than the Mondeo.
Now one thing with the 2.0d's is that you notice the way they're not quite always on the torque in the same way as the 3.0d's are.
My next diesel will be a 3.0d hybrid.
I hope that helps.
Takemeaway said:
Have mostly driven 3 litre diesels for the past decade and been quite happy but with rising fuel costs and a new purchase on the horizon I’m beginning to consider a 2 litre instead which seem to be maybe 25% more efficient and the up front cost an also be significantly cheaper too.
As always there are stories of noise and lack of power for the smaller engine but I’m wondering real world for those who have done this, what is it like to live with on a daily basis?
Have jumped between similar cars with 2.0 and 3.0 turbodiesels:As always there are stories of noise and lack of power for the smaller engine but I’m wondering real world for those who have done this, what is it like to live with on a daily basis?
E90 320D to E61 530D to F31 320D to F11 530D
The 2 litre is perfectly adequate, but once you've tasted the 3-litre you just can't go back and be satisfied...
Perhaps you should try a testdrive with the MB 300de powerplant (4-pot diesel hybrid) or full electric if you like the torque and refinement associated with 3 litre diesels?
ZX10R NIN said:
My next diesel will be a 3.0d hybrid.
I'd love this! But I thought MB are the only ones still making diesel hybrids? Hybrid technology in combination with their new 400d powerplant would be my ideal car, but I don't see it happening with the way diesel is being phased out for passenger cars.A petrol 3.0 hybrid is too thirsty and limited range due to smaller fuel tanks, but soon will be the only option to afford a 6-cylinder company car it seems...
Edited by HelldogBE on Monday 15th November 17:18
Edited by HelldogBE on Monday 15th November 17:19
HelldogBE said:
Takemeaway said:
Have mostly driven 3 litre diesels for the past decade and been quite happy but with rising fuel costs and a new purchase on the horizon I’m beginning to consider a 2 litre instead which seem to be maybe 25% more efficient and the up front cost an also be significantly cheaper too.
As always there are stories of noise and lack of power for the smaller engine but I’m wondering real world for those who have done this, what is it like to live with on a daily basis?
Have jumped between similar cars with 2.0 and 3.0 turbodiesels:As always there are stories of noise and lack of power for the smaller engine but I’m wondering real world for those who have done this, what is it like to live with on a daily basis?
E90 320D to E61 530D to F31 320D to F11 530D
The 2 litre is perfectly adequate, but once you've tasted the 3-litre you just can't go back and be satisfied...
Perhaps you should try a testdrive with the MB 300de powerplant (4-pot diesel hybrid) or full electric if you like the torque and refinement associated with 3 litre diesels?
ZX10R NIN said:
My next diesel will be a 3.0d hybrid.
I'd love this! But I thought MB are the only ones still making diesel hybrids? Hybrid technology in combination with their new 400d powerplant would be my ideal car, but I don't see it happening with the way diesel is being phased out for passenger cars.A petrol 3.0 hybrid is too thirsty and limited range due to smaller fuel tanks, but soon will be the only option to afford a 6-cylinder company car it seems...
ZX10R NIN said:
BMW also do 3.0d hybrids VAG do a Plug in 3.0d Hybrid.
Not really, they don't. BMW offers: 45e (3.0 I6 petrol + battery) in the 5 saloon, X5, 7-series
VAG/Porsche: 3.0 V6 petrol + battery
AFAIK Volvo was the only other brand (beside MB) to offer a diesel plug-in hybrid drivetrain (2.4D I5), but they abandoned that drivetrain already and will be quitting the diesel market soon enough.
All new diesels are increasingly featuring MHEV (Mild Hybrid) technology, which is basically a fancy start stop system consisting off a 48V system with a small 1kWh battery and a small generator/motor that can do some torque-fill (overly simplified). It improves performance and emissions by a small amount, but it's not in the same realm as plug-in hybrids (<50g CO2/km) thus doesn't make a big difference for BIK/company vehicles.
HelldogBE said:
Not really, they don't.
BMW offers: 45e (3.0 I6 petrol + battery) in the 5 saloon, X5, 7-series
VAG/Porsche: 3.0 V6 petrol + battery
AFAIK Volvo was the only other brand (beside MB) to offer a diesel plug-in hybrid drivetrain (2.4D I5), but they abandoned that drivetrain already and will be quitting the diesel market soon enough.
All new diesels are increasingly featuring MHEV (Mild Hybrid) technology, which is basically a fancy start stop system consisting off a 48V system with a small 1kWh battery and a small generator/motor that can do some torque-fill (overly simplified). It improves performance and emissions by a small amount, but it's not in the same realm as plug-in hybrids (<50g CO2/km) thus doesn't make a big difference for BIK/company vehicles.
3.0d Hybrid BMW is the 40d MHTBMW offers: 45e (3.0 I6 petrol + battery) in the 5 saloon, X5, 7-series
VAG/Porsche: 3.0 V6 petrol + battery
AFAIK Volvo was the only other brand (beside MB) to offer a diesel plug-in hybrid drivetrain (2.4D I5), but they abandoned that drivetrain already and will be quitting the diesel market soon enough.
All new diesels are increasingly featuring MHEV (Mild Hybrid) technology, which is basically a fancy start stop system consisting off a 48V system with a small 1kWh battery and a small generator/motor that can do some torque-fill (overly simplified). It improves performance and emissions by a small amount, but it's not in the same realm as plug-in hybrids (<50g CO2/km) thus doesn't make a big difference for BIK/company vehicles.
Assuming you are buying used, is the cost difference really that stark?
Assuming 2.0D vs 3.0D you are probably looking at 40mpg vs 48mpg ish, hardly earth shattering unless you are really piling on the miles.
Do you even need a diesel? Modern petrol cars give far better economy than they used to.
We will be going 2.0T petrol next, fuel economy is not going to be much worse than the 330D we have now and I don't have to wear a glove when filling up
The N57 mated with the ZF8 gearbox is a great combination, 0-60 in five and a half seconds with 40mpg combined is awesome. Having driven the Merc and Audi equivalents, they don't even come close. If you want to spend less, perhaps something like a Mondeo or Insignia as up front costs will be cheaper than the German versions but its not a compromise I would be willing to make personally.
Assuming 2.0D vs 3.0D you are probably looking at 40mpg vs 48mpg ish, hardly earth shattering unless you are really piling on the miles.
Do you even need a diesel? Modern petrol cars give far better economy than they used to.
We will be going 2.0T petrol next, fuel economy is not going to be much worse than the 330D we have now and I don't have to wear a glove when filling up

The N57 mated with the ZF8 gearbox is a great combination, 0-60 in five and a half seconds with 40mpg combined is awesome. Having driven the Merc and Audi equivalents, they don't even come close. If you want to spend less, perhaps something like a Mondeo or Insignia as up front costs will be cheaper than the German versions but its not a compromise I would be willing to make personally.
Edited by Wagonwheel555 on Tuesday 16th November 08:19
Joey Deacon said:
What is the real world fuel saving going to be....
This is the key point. I found that there was no noticeable improvement in economy between a 5 cylinder 200bhp 2.4 Volvo diesel and a 1.6 115bhp 4 cylinder in a similar sized car (S60 vs V60), as you had to drive the smaller engined car harder to make the same progress - with an element of it being so modestly powered that you could drive it flat out everywhere and not be anti-social.If you want a diesel have a 6 cylinder. If you drive a 6 cylinder as if it had only the 4 cylinder power, you will get pretty close to the 4 cylinder fuel economy, but the extra power and especially torque is there on tap if needed
I see no point in a hybrid now, I will wait for EVs to develop a bit more.
I see no point in a hybrid now, I will wait for EVs to develop a bit more.
Lots of interesting points to consider.
I'd not really thought about going for a hybrid although it would make sense as i drive about 15 miles each way to work each day and the majority of my trips are probably around 15 miles/30 minutes in general anyway.
In terms of cost, you definitely get more for your budget with the smaller engine on a used car. An example being an A5 b/e sportback 19 plate with 23k miles vs a 67 plate with 35k miles both for similar money.
And economy wise the savings do add up, there's no debate in that.
Obvious downsides are how refined the engine is and how much slower the 4 cylinder will be in comparison but i'm wondering if i should be growing out of that being an issue, diesel engines are all torquey and have decent acceleration, it's just that some are less rocket like than others.
And then there's the hybrid.....
I'd not really thought about going for a hybrid although it would make sense as i drive about 15 miles each way to work each day and the majority of my trips are probably around 15 miles/30 minutes in general anyway.
In terms of cost, you definitely get more for your budget with the smaller engine on a used car. An example being an A5 b/e sportback 19 plate with 23k miles vs a 67 plate with 35k miles both for similar money.
And economy wise the savings do add up, there's no debate in that.
Obvious downsides are how refined the engine is and how much slower the 4 cylinder will be in comparison but i'm wondering if i should be growing out of that being an issue, diesel engines are all torquey and have decent acceleration, it's just that some are less rocket like than others.
And then there's the hybrid.....
Two E61 (5 series estate) BMWs:
I had a 2007 525d for 3 years. This is the 6 cylinder 3 litre engine, but with a smaller turbo, producing 197bhp.
It averaged just shy of 40mpg during my ownership.
A friend's other half has a 2008 520d. 4 cylinder engine, remapped to around 200bhp by a previous owner.
The car is averaging just over 50mpg.
Same car (both LCI models), same power output, different engines, both with over 100k on the clock. Better economy from the smaller engine.
Of course, the 6 cylinder engine is more refined, very noticeable at low speeds. On the open road, when tyre and wind noise take over, it's harder to tell the difference.
Bigger engine weighs more, has higher internal losses (friction, etc.) and takes longer to warm up.
Given the choice, I'd still go for the 6 pot though.
I had a 2007 525d for 3 years. This is the 6 cylinder 3 litre engine, but with a smaller turbo, producing 197bhp.
It averaged just shy of 40mpg during my ownership.
A friend's other half has a 2008 520d. 4 cylinder engine, remapped to around 200bhp by a previous owner.
The car is averaging just over 50mpg.
Same car (both LCI models), same power output, different engines, both with over 100k on the clock. Better economy from the smaller engine.
Of course, the 6 cylinder engine is more refined, very noticeable at low speeds. On the open road, when tyre and wind noise take over, it's harder to tell the difference.
Bigger engine weighs more, has higher internal losses (friction, etc.) and takes longer to warm up.
Given the choice, I'd still go for the 6 pot though.
I've only had a couple of 4 cylinder turbo-diesels, a BMW 320td Compact then a 123d but I liked them both.
I did 43K miles in the former and 81K in the latter and they both averaged about 48mpg, but as the 123d was a twin-turbo with 201 bhp performance was on a different level - probably similar to a 330d of that era (2007). But it did have the N47 engine that sometimes has cam-chain issues.
If I had still needed diesels my next one may well have been a 330d, but by the time I sold my 123d I wasn't doing business mileage so I went back to petrol.
I suppose as well as better economy the 4 pot might save you a few quid on road tax, and possibly insurance.
I did 43K miles in the former and 81K in the latter and they both averaged about 48mpg, but as the 123d was a twin-turbo with 201 bhp performance was on a different level - probably similar to a 330d of that era (2007). But it did have the N47 engine that sometimes has cam-chain issues.
If I had still needed diesels my next one may well have been a 330d, but by the time I sold my 123d I wasn't doing business mileage so I went back to petrol.
I suppose as well as better economy the 4 pot might save you a few quid on road tax, and possibly insurance.
I haven't had a bigger diesel and gone smaller but I have a 1.6tdi caddy which is the lousy 75bhp model but I think its bang on and more than capable, I've driven my dads audi a5 a few times and that is also more than capable and obviously a hell of a lot quicker accelerating. I really dont think your be disappointed as they're capable, as long as it's not a 1.9 sdi or similar 

Have driven a C250d for last 7 years and not really felt shortchanged. If you step down 3-2 litres then choosing something twin turbo’d would make the gap feel smaller.
Merc now put 245bhp out of the (2 litre) 300d engine with a decent chunk of torque, the sound is the one thing you won’t be able to replicate.
Merc now put 245bhp out of the (2 litre) 300d engine with a decent chunk of torque, the sound is the one thing you won’t be able to replicate.
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