I used to be E55 owner, just got a C63. It seems like C63 consume more petrol than e55?

 

Biturbo vs naturally aspirated?

 

Wasn't the E55 amg supercharged?

 

Yes the e55 was supercharged if you are talking about the w211.

Quick good search yielded:

e55 13/19mpg
c63 12/19mpg


Larger, but newer NA engine versus a smaller, older Supercharged engine. This is just numbers someone with experience can tell you if theres a real difference.

 

More displacement.

 

I can't say about e55 but in winter mode with temp around 2-5 deg c my car in c mode just got 566 KLm per tank which is the most I've ever got

 

Don't let the numbers fool you, the e55 was rated using the older, more generous EPA rating system. In 2008, the EPA revised their fuel economy numbers to more accurately reflect real life figures. If anything, the E55 should obtain the same mileage figures or slightly worse than the C63.

http://www.fueleconomy.gov/feg/ratings2008.shtml

 

I came from an E55 too. The E55 is moderately better on gas mileage than the C63. The thing I forgot is that the supercharger was on a clutch so it wasnt always engaged drinking gas. However the C63 is different, its always going to be drinking gas. Not to mention the fuel tank on the E55 was 19+ gallons and the C63 is 16+ gallons. Its probably a difference of 2 - 5 MPG.