Personally I think aero is the biggest limiting factor. You can make carbed motors get great mileage, just look up Mobilgas Economy run. Given these cars and drivers were a little on the extream side, but it shows carbed motors can get good mileage.
I am saying this and I own a gen 3 swapped 63 pick up. Now mine is not meant for mileage as it gets about 10-11mpg on the freeway right now. I think I still have 2mpg to pick up once I lean it out for freeway cruise, but this is a 410 rwhp combo through a 4L80E tranny which is known to suck the power (460rwhp 6 speed combo). I have a 3,200 stall in it (locks on the freeway) 12bolt with 3.73's and a 26" tire.
If this wasn't a drag truck I would have a late model 6 speed in it and I'm sure the MPG would pick up even more (6th is a .5 vs my current .75 overdrive)
The heads cam combo was once in my buddies 2000 F-bod. His 4L60E 3.23 geared car would knock down 23mpg on the freeway.
Last edited by Super73; 11/05/2007 4:35 AM.
