Ok I have been thinking about this for a long time about making upgrades to my vehicles in order to increase gas mileage. Obvious things are, better free flowing Air intake, better exhaust perhaps a header.
I have two vehicles, a 2002 Toyota Tundra V6, which contrary to publisized mpg get much better gas mileage than my friend V8 of the same make, model and year. Our second Vehicle is a car, a 1998 Toyota Camry, and I hope to get it up over 30 mpg soon, and that shouldn't be too hard as it gets as much as 28mpg just the way it is. My dream would be to get it over 40mpg, but I don't know if that is even possible with the current engine.
I have experience in rebuilding engines, doing many performance modifications myself, so much of this stuff should not be too difficult for me. I just need to talk about it and benefit by others experience. I have in the past tuned engines to get their best gas mileage at a specific highway speed, by cam timing, port and polishing heads, valve size increase and so on. The thing I need to update myself on is how to work with the electronic sensors and computer stuff.
Obvious things are, better free flowing Air intake, better exhaust perhaps a header.
While obvious and intuitive, they would not actually help an economical driver. If they flow reasonably enough to make a lot of power (high RPM + open throttle), they will flow completely unobstructed at mostly closed throttle (regardless of RPM) or low RPM (regardless of throttle opening). An intake or exhaust that is so restricted as to affect ecomical drivers would be worthless if you ever need any power (say, merging on the highway uphill).
That's not to say that you can't do any modifications to help; indeed, with your considerable engine work experience, you may be able to do something useful. Look for other threads, there were a couple good threads in the past month or two where people talked about building an engine for economy.