E66 Petrol vs Diesel real life MPG's

[bigdom]

After reading various posts on diesel issues, I'm now considering going back to petrol as part of impending car purchase.

Any views on mpg difference?

[E38Ross]

What sort of driving will you be doing? Diesel will be more economical on fuel of course, but the petrols will be smoother, faster, cheaper to buy and less likely for massive bills on the engine front at least.

[AreOut]

what's wrong with LPG? Get the best of both worlds, and its boot is quite big.

[E38Ross]

AreOut said:

what's wrong with LPG? Get the best of both worlds, and its boot is quite big.

LPG you do lose a little amount of power, more so with higher performance engines, mind....more so when compared to RON99 fuel.

[bigdom]

Commute is 12 miles each way, mainly fast A/B roads.

Overall mileage 15-20k pa, both sets of outlaws 200/250 miles away, plus a few trips across europe in the summer months.

[AreOut]

E38Ross said:

LPG you do lose a little amount of power, more so with higher performance engines, mind....more so when compared to RON99 fuel.

with modern systems its 5% at most..and it would still be more powerful than diesel no?

[Patrick Bateman]

AreOut said:

what's wrong with LPG? Get the best of both worlds, and its boot is quite big.

Short of finding a car that's already got it, the cost of getting it done.

[pilchardthecat]

AreOut said:

with modern systems its 5% at most..and it would still be more powerful than diesel no?

Compared to 95 or 99?

[AreOut]

yupp, LPG is 105-110 octane...albeit lower calorific value

liquid injected LPG can yield even more power with appropriate tuning

[JNW1]

bigdom said:

Commute is 12 miles each way, mainly fast A/B roads.

Overall mileage 15-20k pa, both sets of outlaws 200/250 miles away, plus a few trips across europe in the summer months.

I'm not familiar with the E66 range so what's the engine choice - V8 petrol or 6 cylinder diesel? Based on experience with other models I'd say diesel will be more economical than petrol but probably not by as much as the published figures would have you believe (and I suspect your short commute will hurt the economy on the diesel more than it will the petrol). Personally I'd lean towards petrol although to be honest an E66 doesn't strike me as a car you'd jump in for the fun of driving; therefore, if what you're after is something that just wafts along at relatively low cost the diesel possibly makes some sense.....

[bigdom]

Engines are either 3L Diesel, 3L Petrol (too small), then V8's either 4, 4.4 or 4.8L.

[Bubba Zanetti]

bigdom said:

Engines are either 3L Diesel, 3L Petrol (too small), then V8's either 4, 4.4 or 4.8L.

If I'm reading this correctly, you are saying the 3 litre diesel is ok but the 3 litre petrol is too small?

If my memory serves me correctly the 730i has more BHP than the 730d.

Obviously BHP isn't the be all and end all...just trying to understand your reasoning.

[bigdom]

The 3L petrol whilst more bhp than the diesel, is light on torque for moving a 2 tonne car Imho, so has to be a choice of a V8 or diesel.

[AreOut]

since both are autos it's quite irrelevant..and because of gearing petrol will always have more torque ON WHEEL than diesel, this we sorted out in a 335i vs 335d thread

[martin mrt]

AreOut said:

since both are autos it's quite irrelevant..and because of gearing petrol will always have more torque ON WHEEL than diesel, this we sorted out in a 335i vs 335d thread

Not irrelevant here, the 3L petrol in this case is naturally aspirated and quite a bit behind the 3L diesel in the torque department, regardless of whatever calculations/comparisons you make it's still going to be behind the diesel.

335i 335d is a real comparison as both are turbocharged

[AreOut]

huh they produce 3.0 NA E66? didn't know that...now I see that petrol one is still slightly faster in acceleration despite having no turbos

[bigdom]

All the petrol engines are NA

[bennyboydurham]

I've got a 730d. A short commute does hurt the fuel economy but if you're doing 15/20k a year then the diesel is a no brainer. Mine easily returns 30mpg around town and any decent run you'll be knocking on for 40mpg. A good constant speed run will get you up towards 50mpg. For a car with this kind of space and comfort that's not to be sniffed at.

I think you might find a 730i a bit lacking in grunt for a car this big (if you can find one, they are very rare!) so you'll need a 740,50 or 60. The 750 is supposedly the best of the bunch and makes a wonderful noise but you'll be lucky to get high teens in terms of mpg most of the time!

[bigdom]

I went and looked at a couple yesterday, 730d & 740i, the latter clearly has the edge. The issue now is if I buy an AUC car i get 12 months warranty thrown in, although after a quick play on the site, it's £165 pm, or £100 more pm than a 5 series when I need to renew!

[bennyboydurham]

Yes extending the AUC warranty on an E65 is ruinous. Stick a couple of grand in the contingency pot, find a good indie - job jobbed. I'd have paid out 6k by now on mine if I'd kept it up and my warranty claims would have been -£nil!