18 km per liter = 42 miles per gallon

I've read on CNN.com a long article about hypermilers. I've read on WIRED (April 2008) about a fake company that promised electric cars and, to go with them, a Smart Fortwo that scored an eco-friendly 37 mpg (15.7 km/l).

Yesterday I filled the tank on my FIAT Seicento (1100cc unleaded fuel engine) with 31,61 liters. I had driven 575km (357 mi), on highway, countryside (80%) and suburban, with an average 70 km/h (44 mph) speed limit. With some easy math it turns out to be 18,19 km/l (42.78 mpg). Cool!

My urban average is between 14 and 15 km/l (33-35 mpg) driving 20-25 km per day.