This is a fascinating article by C&D's editor Csabe Csere where he suggests taking a 3 series with the light magnesium alloy engine and turning it into a car with 37 mpg that can run with the last generation M3.
I have an '06 330. When I hypermile (shift to neutral when going downhill and drive carefully). I can pull 33 mpg average.
BMW aero kit
Dinan Ram Air
Nothing in the trunk
Several ideas to make Csabe's dream car:
CF hood, trunk and doors
Supersprint tubing/cats (they are steel, need aluminium to titanium)
Light suspension components (?)
Ultra-light 18 inch rims
Ultra-light braking system
I'd prefer not to dump the runflats.
Any more ideas to make this car happen. We all hate hybrids and want to make an example of a practical sports car with great mileage.