I wouldn't dismiss the French option out of hand - Renault, PSA and Audi/VW/Merc/BMW have had good and off days with oil burners. If you are willing to consider it a 205 DTurbo is a fun little rocket, not the 1.9 from the 405/306 but a non-intercoolled 1.8 but still pretty quick. There were some run-out "Mardis-Gras" models with DTurbo engines which are little sleepers but they were made in Morocco which last time I checked is not well known for car production.
However if you are going to stick with German then how about an off the wall suggestion - a 190D - 2.5. Basically take the engine out of a E-class 250D and mate it to the chassis of a 190E-2.6 (with the modified bulkhead). Auto and manual options. And none of the rust problems of the C-class. Oh and very veggie-friendly.
Or even if you are willing to go Brit then I would have a local search for a late Rover/MG model with the Diesel 2.0 turbo. I had a test drive in a ZS with the 115hp lump and it flew, and the old Rover 200/25/ZS chassis was good enough for me to pass and outrun a Focus 2.0 Ghia on the A701 in my 220SDi in 1997. The Rover 200 models rusted a lot but I think the 25/MG ones are slightly better.
Or for ultimate cool and mega MPG an AX 1.5D - veggie friendly and you know you can get 80 MPG out of one.