I drove 114 miles last weekend to a car show. The route was stop and go and about half freeway. My setup is a 540ci HEMI with (2) 750 Hollys on a Stage V intake. The cam is 248/254 @ .050 solid roller. Compression is 10.8. The 727 has a 3500 converter and the Dana has 3.54 gears. The car averaged 10.8 mpg. When I first started driving it the mileage was 7-8 mpg. I tuned the carbs with a vacume gauge and hooded up/tuned the vacume advance in the MP distributor to get the 10.8 mpg. I don't think that is too bad for a 4000lb car and a 540 ci engine spinning 2800-3000 rpm on the freeway.