I think some of the high rpm gearing may be the result of strict emissions testing...I don't know, I'm guessing. Possibly less carbon, hydrocarbons produced from the engine working harder? I've noticed that my wife's Stratus runs around 2,600 rpm at 65 mph and my old Spirit (auto) was only 2,100 in OD at the same speed.
My 85 CRX HF was at 1700 at 55, and 2500 at 80. Those were the good old days.
When I swap in the hf tranny to my 91 std civic hatch (with SVOboy's help of course), i will have reached a decent baseline of I'm hoping 45mpg highway. With the 4spd std I get 40mpg highway. I will be running over 1000rpm less than what I am at now on the highway! I got coroplast, and want to do some aero, and add vx rims = good for 50mpg? I am with DaX on 50mpg...a good round number.