[Saturn1994]

What I have found is that best fuel economy is based on load. I haven't got a good method for measuring load (manifold pressure is one way). However, I do have a rule of thumb, and I have it somewhat automated: I manually accelerate to 30 or 40 mph, and then engage cruise control. If on a fairly level surface, I can press the + button every 1 second on my 1994 Saturn SW1 SOHC, which will give me fairly smooth 1 mph acceleration every second (i.e. to go from 40 to 60, pulse the button 20 times). If on an incline, I need to increase the time between pulses depending on how steep the incline. What I try to avoid is pushing the ECM to drop gear and accelerate the engine, and to avoid loading the engine so that the ECM enriches the fuel mixture.