A further narative with question instead of a real response to the original post. I have never had a Mercedes gasser, so I can't speak to its costs to be sure the comparison is valid,

But I've owned for years a large Audi, so maybe it approximates something of a mercedes gasser. On long distance I-80 type travelling The Audi is a pleasure to drive and gets great gas milage of 28 mpg when its running right. On the other hand, for around town driving of buying groceries, going to the bank, the kids school etc. it gets lousy gas milage and just feels too big.

Even though I've had the diesel only a couple weeks, the fuel costs are a lot less than the audi's for real city driving.

So in a sense I'm asking for confirmation heavy car for heavy car if a diesel's in city gas milage costs is much less than a gassers?