Let's Have an MPG Thread

Recently had an email from WhatCar? regarding their True MPG data.

Got me looking at several of their tested categories. Still appears that the latest performance petrol engines (like the 435i, M135i & M235i) hold up much better against the official NEDC figures than your typical diesel engine. WhatCar's results bring in the above petrol models at less than a 10% shortfall, whereas performance diesels have a greater shortfall, against published combined figures.

This is something I have noted for years, and even with stretching reality even more these days with the test results, we still see a closer (petrol vs. diesel) real world consumption for performance engines than official figures indicate.

Peter

 

Yes, my old N53 3 litre petrol E61 would easily do 37mpg on the motorway, my current 530d will do 40/42mpg at similar speeds. Not a massive difference. Another way of looking at it is the range, with my short journeys the diesel is only about 50 miles better off per tank full.

 

My N47 2.0 diesel with the 8 speed auto is excellent upon long runs. Managed 52mpg from Cornwall to Birmingham.

Also did Calais to the Vendee coast 430 miles in 5.45 hours including stops peage and fuel averaging 47.5mpg (average speed was 73.5mph) we were late!

Overall the car has averaged 44mpg in my ownership. Certainly could do more but I tend not to drive for efficiency.

 

330d is certainly not a compromise, it is a properly quick car.

yes I noticed that as well, maybe the torque of the current engine is too much for rear drive?

 

I'm guessing but 45mpg should be easy without economy driving (for long journeys). I can easily do 42mpg in my 530d at 75/80mph.

 

I'm assuming you are really looking to compare a 320d with a 330d, to see what the day to day penalty will be in your kind of driving.

I'm going to suggest it may not be very different in real world driving. From experience it is only when you drive light, does a smaller engine in the same body (assuming transmission, etc., are equal) really improve on the bigger engine. As you drive loaded trips with higher average speeds, I believe mpg will be pretty close and worth the cost, for improved overall performance and refinement.

As an example, my son has run an E83 X3 2.0d manual, (best economy) vs, his current E83 X3 3.0sd auto. Economy difference long term, a couple of mpg. Yes, about 2mpg for a completely different experience. One, an unrefined drive, required working the engine pretty hard for the same relaxed and refined drive in the 3.0sd. Plus the 3.0sd can get up and go when required.

Peter

 

Mine have been petrol, but the MPG differences between my 330CI sport and my 335i sport are minimal to be honest. The 335D on the other hand is quite economical. And an M3 eater at 30-70mph. You know you want to

 

The reason for posting and referring to something like the WhatCar? true mpg figures, is WhatCar are trying to get a "real world comparison", in conditions similar to many users. They do state their own test regime mpg shortfall against the official NEDC tests are an 'average' of 20% We know any test doesn't cover all the variables, but WhatCar does test each example over the same ground, therefore results give a better feel for fuel efficiency of a given model.

It is in this set of conditions where the higher performance petrol engines do show that the mpg gap is not as wide as the NEDC tests indicate, from their laboratory comparisons.

Peter

 

Think I might pass on this topic

 

Go on, make us all feel better about not owning an M5.

 

Initial MPG as follows , Don't care !!! ( although not too bad )

 

It was the fact a more powerful engine could give better fuel efficiency, that got me interested in MPG figures many a year ago.

Like you, I had the more powerful car (Cortina 1500 GT), my mate a 1200 Cortina. Driven the same sort of pace and use, my car was much more fuel efficient. Plus I had the performance when I wanted to use it.

The key point to factor in is driving both cars a similar way. Guys driving 328i vs. 335i in the US are finding the same sort of result. Drive a 335i within the performance envelope of the 328i and there is not really anything in real world mpg. It is when you use the additional performance, where the bigger engine will of course drop off in mpg.

I guess a couple of test drives will give you a good feel for the mpg differences. A spirited drive in a 320d, then a similar paced drive in a 330d and see what the penalty is.

Peter

 

In prep to sell the 640d I took these pics ..



Although they were tainted as theres a lot of 50 zones in there, and I was steady.
I did have a pic where it was up to the top for 8mins - lol. But then miss daisy got out, I chucked her out as I couldn't bare it any more.
Average was 29 including a lot of short urban.

The Porsche does 40mpg (including electric charges), with a range of motorway and urban. Urban for my normal use it uses none.

 

I noted your figures in the running report. Surprised me a little, but have noted the latest 1-series are not giving high figures across some of the user fuelling sites. My brother in law has a 2009 E87 120d M-sport manual and he gets pretty good mpg driving in Swindon and area. He has no problem getting over 50 as an average, and has seen 60+ on relaxed runs. I'm a bit surprised to be honest, as he is not a slow driver and uses the performance.

Peter

 

The return journey from picking up my 525d (3.0) from Derby gave me 47mpg averaging 70 leptons which was as good as I got from my 2009 E61 520d and 10mpg more than I got from the 730d in similar conditions.

Since then I've returned mid 30's knocking around (730d gave me early / mid 20's pre thermostat replacement and mid/late 20's after).

I suspect the bulk of this improvement is down to the 8 speed box which is excellent. I'm still not over the gearing in top - circa 46mph/1000rpm.