what rpm for optimum fuel economy? - The Unofficial BMW M5 Messageboard (m5board.com)

mkiv98 · 14th August 2006, 08:09

what rpm do you guys shift at for optimum fuel economy?

SpecRaceM5 · 14th August 2006, 08:57

I think people get to caught up in the RPM. I could be wrong but your gas millage is going to be determined by the amount of throttle you give the motor. So that being said the optimum shift point would vary by the slope of the road you are driving on. If you are going up hill, a lower gear would give you higher rpm and since the powerban is higher on these cars, you would require less throttle. Down hill put it in a high gear, low rpm less resistance from the motor hence less need to push on the gas.

Correct me if im wrong.

vadas1 · 14th August 2006, 10:11

Quote:

Originally Posted by mkiv98

what rpm do you guys shift at for optimum fuel economy?

Just out of interest. Why do you worry about fuel economy in an M5?

ralph (vadas1)

Chas C · 14th August 2006, 10:20

I've found the M5 to be surprisingly consistent - regardless of RPM or driving style it seems to return around 20mpg. Cruising all day at 60mph can get up to 24mpg but if that's the kind of driving you are doing then the M5 is the wrong car to do it in.

BURTON · 14th August 2006, 11:01

I have found that around 3k seems to be good.. But thats with a 5spd car. Through town and motorways.. theres no difference between 40mph and 100mph for instance..

StevieBoy · 14th August 2006, 21:54

Drive it like you just stole it and forget about the fuel

Live a little

Perhaps die quicker too but hey!! ...... go out in style

Geach · 14th August 2006, 21:58

Quote:

Originally Posted by StevieBoy

Drive it like you just stole it and forget about the fuel

Live a little

Perhaps die quicker too but hey!! ...... go out in style

I agree,stuff fuel ecomony!

Sebring NL · 14th August 2006, 22:06

I tried to get as far as possible on a tank once, trying to get 600km from 87 litres.

I would like to see what one of those regular E34 econometers would read in the S38.

Personally, I can't care less for fuel economy as I am 4 miles from the office, but I understand some people would like some pointers.

I would never ever apply any throttle below 2K revs other than in first gear. Frankly, when I drive the car with the aux air pump still on, I shift on 3,2K and watch it fall back to a tad over 2K.

After a high speed run and a sudden slower section, I like to stay in a high revs/ low gear so oil pressure will be high. Tomba's fathers 3.6 threw an oilpump after dropping the throttle after Autobahn speed. I think in some cases its inevitable, however some nice high revs mean high oil pressure when you need it.

I think "undershifting" the E34 M5 will cause the engine to become "lazy" and thus less economic. Leisure drives are between 3 and 4K revs for me. Never below that,as soon as the engine oil reaches 90ish degr.

If any economy can be gained from underdriving the car ( which I doubt!) it will give you a cause to spend the saved money on a nice engine rebuild..Now, where would that break-even-point be? 5.000.000 miles a year?

hertfordshire1 · 14th August 2006, 23:09

I have a simple method for getting good mpg in my car.

Leave it in the garage.

Steve

nixter · 14th August 2006, 23:11

I didn't buy mine for the fuel economy

However, i seem to have abismal fuel economy! I haven't reconfig'd my obc yet but at half tank the odo usually says 175 - 200 kms. Granted this is with pretty much all inner city stop and go driving. Still seems poor to me though.

n