I just took the longest trip since I owned my Insight - 250 miles each way - and was looking forward to keeping the car in lean burn most of the time. Although I managed to average 70 mpg going and 65 mpg coming back, I found that once the car went into lean burn it almost immediately began to lose steam. Is that how lean burn works - you get it going (so the instantaneous meter reads about 100), the car slows down, you accelerate to your desired rate of speed, enter lean burn mode, then repeat? Or should the car remain at a constant rate of speed while in lean burn mode if I were more skillful? If the latter, how in the world do I do that?