How bad is bad? The 4matic system costs a bit of mileage, due to the added weight and the added driveline friction. An E320 4matic is rated lower both in city and highway mileage than a RWD E320. An of course the V8 costs in terms of mileage. Is it perhaps 3MPG worse - maybe 17 around town and 22-23 on the highway?

- JimY