Fuelly Forums - Dropped in since my other MPG board is gone

I use to belong to mpg Research and they went Bye Bye it seems.
I've been into getting better MPG since about 1997.
Presently own a 1987 Volvo 740 Turbo wagon which I have been modding since about 1997. I also picked up a 1997 Volvo 960 which is my dedicated highway car.
The Volvo wagon mods came out of a need more than a want. I drive 1180 miles each way to visit family in Naples Florida. Which meant having to stop for fuel every 325-340 miles. When you have been on the road 18-19 hours that last fuel stop 100 miles from your destination is frustrating.
So I was going to go the easy route and install a bigger fuel tank (80L) from a newer sedan. Well being I own a wagon that wasn't going to work, not enough room under the car.
Well then I had to look at getting 50 to 75 miles more out of a tank of gas.
24 mpg highway was not enough I needed at least 28.5 mpg.
Started by lowering the car and removing the roof rack for better aero numbers. I ripped out the automatic transmission and rear end and replaced them with a manual transmission and the highest gears I could pull out of a Volvo in a junk yard. The car originally had 4.10 rear gears and now has 3.31 gears. Replaced the 15 inch wheels with 16 inch for just a little more drop in rpms. Filled all the fluids in the car with synthetic and I got to my planned MPG. Today the car at 65 mph will pull at least 29.5 to 30.5 mpg.
Not bad for a car with 359,500 miles on the clock and a original Cd of .39.
Soon to be retired at 400,000 miles.
I just started playing with the 960 since I just got in in Feb 05. Best I could pull at 65 mph was about 25.5 mpg. Cleaned out the motor with an Auto-Rx treatment and saw a quick 1-1.5 mpg increase. I guess a internally clean motor is a happy motor. I did some custom sheet metal mods under the car, filled it will all synthetic fluids and raised the tire pressure from 36 psi to 40 psi. Now 28.5-29 mpg highway are the norm at 65 mph. 3600 lbs and .36 Cd make any gain in gas mileage a gift. Lowering it is economically unfeasible. The kit available from Volvo is grey market and $2500. Looking this summer at extending the front spoiler down another 1 to 2 inches. Also looking into getting rear wheel opening covers made that can be snapped on and off easily.
One reason I hang on these boards is when I replace my wagon I want to get a very fuel efficient vehicle to start with as my daily driver. I want at least 24 to 25 city and at least 35 highway.