Haha, exactly the same case as mine. Bought a 2013 Sprinter as well iski pehle 1000KM tak mileage 38KM/L thi(what a coincidence that you have exactly the same). Don't worry, after adjusting the mixture on first tuning it started giving me 55+KM/L. You just have to wait till the first tuning. Running itni par hi karain