I am trying to figure out if my car is odd or if it is me.

I get about 9 mpg in town and best case scenario about 18 mpg on the highway - these are much worse than any of the tests and I can't figure out what I am doing wrong.

What kind of consumption do y'all get and what tips can you share?!?

 

Can't specifically tell you, but ballpark this sounds about right. The official numbers are 14 mpg city and 21 mpg highway. You are not gonna get those, unless you drive like a grandma. Getting within 2-3 mpg of the rated highway mpg is about what to expect in the real world. Your city mpg also doesn't surprise me. With lots of stopping and accelerating, that's pretty much what you are looking at. The test cycles have lots of idle time where start/stop makes manufacturers look good, but if you are not regularly stopped 7+ seconds with the engine off, you are not going to see much benefit of ECO start/stop. For comparison, my C63S coupe with the 9 MCT is supposed to get 17 city and 26 highway. On a long highway cruise with DISTRONIC I get around 23.5, so about 2-3 lower than rated like you and city I see as low as 11, so up to 6 mpg below rated (I turn off ECO start/stop). Just depends on how heavy my leadfoot is that day. These cars are about smiles per gallon, not miles per gallon .

 

Never bothered to calculate MPG. I know that the M177/178 engines are thirsty in daily traffic. Our GTC goes between 200 - 230 miles a tank, which was similar to the E63s. The M8 maybe gets 280-300 miles, so definitely lower in its consumption.

 

+1...never bothered to calculate it. Just occasionally check what the Mercedes me connect app says about the most recent trip out of curiosity. Just for further reference, took the C63 on an errand with mixed highway and city driving just now. App says 17.5 miles, average speed 23 mph and average mpg 12.8 mpg. I just noticed that my lifetime trip data got reset, probably during the last service where they updated the engine software, but from what I remember my average over the last ~30k miles was about 15.8 mpg. The SL is heavy and the aerodynamics are somewhat poor due to the ragtop, especially if open.