All car forums gotta have one of these threads:

My W202 C220 does 550km to a tank (59L). It's been consistently so for about 4 or 5 tanks now since I picked the car up. So that makes roughly 11L/100km mixed driving. I'm very pleased with the result is quite coherent to US government's test: 8.4hwy 10.2city and I have heavy foot and 18" wheels to spin.

what are your figures?