my old man has a 98 e300 that gets around 31-32mpg and I ended up buying a 99 e300 because I wanted to get the same type of economy hes getting. I got a good deal on a 99 black/black e300 for 9k that had 166k miles and chrome AMG wheels. After driving it for a month i'm only averaging between 26mpg or so and i'm confused why i'm getting worse economy on a car thats pretty much exactly the same as my dads.

the only conclusion I can come up with is that the chrome AMG wheels on my car are much much heaver than the stock aluminum ones on my dads car...but could that really make me lose almost 5mpg?

also i have a slight knocking noise when I first start the car up when its cold that goes away when its warm. It sounds like your hitting a hammer on a solid piece of steel at random intervals...any ideas on what that could be?