After having my stock 1950, 3600 216, w/4sp and a 4.10 gear for about five years and keeping very meticulous records of the mileage and tuning touch-ups about every 500 miles my averages run between 14 to 15 mpg. Realistically I’m expecting between 15-17 mpg on the hi-way unloaded and 14 -15 mpg around town. So that’s been my experience and I’ve got the log book to back it up for the last 8,000 miles.
It’s indisputable that you will get the best fuel mileage with any vehicle at between 25-35 mph simply because of the drag that has to be overcome at higher speeds.
A 3.90 or 3.55 gear will increase your mileage if you drive at a steady 35 mph but not if your running the express way at 75 or 80
i agree with you denny. i keep very accurate records on all three of my trucks. even though two of them are rated for 16000 gvw and my 40 is a 250. the best i can get on the big ones are around 8-11 and 11.5 to 12.5 on the 40. top speeds for me is 53 mph that i run. im not dissappointed because i realize the dynamics but im always striving for that little bit more and havent found it not to say there isnt anymore to get.
