I just want to confirm, The 540i and 740il use less fuel then their M30 3.5 litre brothers correct?

Pretty similar probably. I think the V8 cars might get a little better on the highway.
If you want to check the EPA mileage specs go to:
www.fueleconomy.gov

Seem to be very simliar on the highway. I think a slightly modded M30 could pull just a little bit better mileage than what you'd get out of an M60, but I could be wrong. I've gotten just over 27mpg in ideal conditions out of my M30 (with chip and better injectors), and I don't think you could get a M60 to do that in the same conditions.

I really don't think a 740il would get the same...even on the highway you're talking about a decent chunk of extra weight there.

Seem to be very simliar on the highway. I think a slightly modded M30 could pull just a little bit better mileage than what you'd get out of an M60, but I could be wrong. I've gotten just over 27mpg in ideal conditions out of my M30 (with chip and better injectors), and I don't think you could get a M60 to do that in the same conditions.

I really don't think a 740il would get the same...even on the highway you're talking about a decent chunk of extra weight there.

Anyone looking for good fuel economy should look elsewhere. Any number of V8 GM & Ford cars get 30 MPG+ on the highway. My 5.7L 6spd Corvette got 20% better gas mileage than my 4.4L 6spd 540i. Economy is irrelevant when you own a car stickering for $50K+. Some kids making minimum wage drive 4WD trucks getting 10 MPG & they find the cash.

My m20 gets 12 mpg (13 if I'm lucky) and I find a way.... :buttrock
lol.. economy should be somewhat of a factor, just not a HUGE one. The 4.4l and the m30 in my experience are VERY similar in fuel consumption. (both better than mine) lol

I am averaging just about 14mpg, and that is about the same as my 03 Expedition and 03 Avalanche. I am not crying, I knew what I was getting before I bought it.... :alright

If you're really concerned about MPG, the 93+ 525i gets very reasonable mileage.

My E34 M50 525iT gets very similar mileage to my E39 540. In fact, I think the 540 gets better mileage on the freeway due to the extra gear and more modern fuel management.

So, in conclusion, the 540 is fairly fuel efficient compared to the I6 motors.

This MPG has been covered many,many times.But I like a little shared info so:on my 535i 5speed I get 19 city and 24 hywy.In my 540i S/C 6 speed I get 18 city and 26+hywy.NOW when I 'put the pedal to the metal' I get 9 MPG in my 540i. :redspot