Fuel Economy?

[Whit]

I have a 1988 BMW 750il. What kind of fuel economy should I expect? City? Highway? Mixed? What steps can I take to improve it? I am only getting about 2.5 to 3 km per liter or about 7 mpg max. I know this is a V-12, but another guy I know gets over double this. Anyone?

[Whit]

I know it IS bad, huh? 7 mpg seems crazy to me. I have a friend who gets 18 mpg on the highway in his 750. How can I diagnose this and repair/replace the correct items? Specifics would be good--even a website or two. Thanks.

[shogun]

Whit,
mileage is a very wide field. Normal is:
according to DIN
at 90 kmh 8.8 liters for 100 km
at 120 kmh 10.9 liters
city: 20.8 liters
That is what the owners manual says.
If I drive in the city ineed 20-25 liters for 100 km. Autobahn at 100-150 kmh = 12-15 Liters.
Items to change: spark plugs, injector nozzles, dizzy cap and rotor, oxy sensor.

[Whit]

Thanks, shogun!