Since my speedometer is off due to running smaller than stock tires(less than 6200 miles on a 70,000 mile tire, so wont be replacing these anytime soon as previousily mentioned), at 74 on the dash I am actually running 70 on the GPS. So at 74 on the dash, Im right around 2900-3000 on the tach. With the dash reading 79-80mph, where it normally is because I hate getting up in the morning, is right around 3200-3300rpm. I drive TO work not for work. I cant take my backseats out though, because I get my son every other weekend and Im not willing to take the seats out, just to put them back in 10 days later. To me its not worth that little gain in MPG to do that.
I just had a 18 inch long 2.5 inch glasspack installed in the exhaust, and I honestly dont THINK I have changed my driving style(maybe I have), but I am now seeing closer to 25MPG now.
Also, with the speedometer being off, I have done the math, for every 100 miles I drive I need to subtract 5 miles off what the trip meter says. So if I go 200 miles on 10 gallons, then in reality, I went 190 miles. So even though my last fillup said I went 258.8 miles, I really went 248.8, netting me almost 25mpg. I also do not have cruise control, but in normal conditions, I have gotten pretty good at keeping the speed with 2mph at all times. As for the A/C, I never use that in the summer unless my son is with me. I prefer the windows down if I can.