My E92 gets about 400km per tank if you drive combined city / highway, and don't drive to the last drop-- which would work out to about 14 L/100km, which isn't bad for a 4.0L with 414hp!
My trip computer tends to be a bit optimistic, but not by too much, showing about 13 L/100km.
Highway, it will do about 11 L/100km (or about 550km), assuming relatively constant 120-130 km/h speeds.
It is only a 63L tank, so not all that big, but more than enough range, IMHO.
To get only 300km, you're in the 20L / 100km range, at which point you need to be doing a lot of moderate-to-full throttle driving, which is pretty tough to do, but impressive.
You basically pay in mileage for engine volume and hp-- my E46 M3 gets about 20% better mileage, not suprisingly with about 20% less power, and exactly 20% less volume.
I say buy my '08, and have a ton of gas money left over so you can drive-it-like-you-stole-it as much as possible!
Last edited by Linz323; 08-22-2013 at 02:00 PM.