Driving style and climate makes a big difference. The AC compressor can demand 5-7 hp. Then there's fuel. With most fuel (including most major brands - not just generics) it's rare to get better than 28-30 mpg from my 190D 2.5 turbo (same 602.96x engine as in your car) but BP/Amoco usually delivers 32-35 mpg under the same conditions (summer driving - AC functioning). In spring and fall I usually get a little better mileage.

When fuel supplies get tight (as they have been during the last 5-6 months) it is usual for the engergy content of most diesel blends to drop to the absolute lowest tolerable limit - and the lower the energy content, the more fuel it takes to go the distance at whatever speed. BP/Amoco has maintaained their energy content better than the other majors in recent years (although a few years ago, even they dropped the ball for several months). Itb is NOT unusual for the fuel mileage to dro[p by 20% when fuel supplies get tight just like it does in the winter when D #1 with it's lower energy content is mixed with #2 to prevent gelling.

Marshall