The only time I got near 40 mpg on my 5-speed TBI Daytonas is when the national speed limit was 55 mph and I was traveling on long highway trips with cruise control set. I averaged 40 mpg from MA to FL and back. Later from MA to VT where the speed limits were 50 and 55, averaged 38. But lifetime average was 34 mpg, and now with my 93 Daytona I can't get better than 32 mpg. I blame it on the ethanol gas, which is all 10% in this part of the country.