This is unfair because its canadian but my Smart CDI was quite good. I would race it around in kamloops(hill city, traffic, -30c to +45C) for a lifetime avg of 4.2L/100km
https://www.fuelly.com/car/smart/for...mespeed/759642
My 2001 corvette uses more fuel rolling down a steep highway hill than the smartcar used coming up the same hill at 100km/h.