The engine in the Mercedes Benz C-Class is the 2 litre and this offers up 4 cylinders and 241 horses. You may be able to get around 24mpg from it when in the city and on the highway you can get around 31mpg. The V6 version offers 21mpg city driving and it you choose the 3 litre you should get about 29mpg.
The BMW 3 Series offers up the 2 litre engine and this offers up about 23mpg in the city and when you take it onto the highway it offers around 35mpg as it comes with 240 horse power.
But would you prefer to be behind the wheel of the BMW 3 Series or would you rather have the Mercedes Benz C-Class?