The trouble with the 524TD BMW is that you have a very limited number of sources for parts. Tons of sources for the E28, but that engine was only in a model year or two, IIRC. Also used in some obscure, very underpowered motor home, and actually used in a Lincoln Continental for about a year or so.

Stick with a MB. I get 33 MPG on my '95 E300D.

Rgds,
Chris W.