Ed, i don't know this for fact, but I've read a bunch of different places that the VW drivetrain absorbs 10-15%.
I wonder if that also holds true for the Rabbit and all other transverse FWD cars?
It would make sense that they consume even less. The torque never changes direction(90 degrees) like in a Bug.
I've seen some Spyder tests that have about a 160-170 or so hp engine and the tested 1/4 mile time calculated out to about 145 wheel hp.