I got 36 mpg on my first tank, without even trying to be careful, let other people drive it, did some quick takeoffs and some highway driving at 85. Then I installed the scanguage right before the 2nd tank. Now I am averaging 44 mpg in the city. That feedback from the scanguage really makes you watch it. I think 50 mpg is possible, but you might tick off the people behind you, and I don't want to give them a bad impression of the Smart.