You should check out my thread on the G1 Insight. I've had basically every issue stereotypical of the car, and nearly all of them were quick and simple fixes.
http://ecomodder.com/forum/showthrea...ild-29288.html
Lean burn took me a while to figure out, but here's my basic understanding of it:
In 5th gear, accelerating with 100% load, you're at 45-50mpg. If you let off the pedal gradually until you reach ~100mpg, after a moment the car will drop into lean burn and shoot up past 150. You can then press the pedal back in to around 75mpg. Anything beyond this and you're at ~100% load again and it will drop out of lean burn and begin electric assist.