[gnu]

K series work for me; I've had five. I do a low mileage (say <6k mi p.a. each) on the 75 and 25, and the 25 does a lot of short city runs. K's warm up quickly, are pretty simple and pretty economical. For me, a diesel wouldn't work, on the 25 at least. Plus, the city where I live is just the sort of place that will ban diesels in the future.

On the down side, k's do need to be watched, so are not the engine for you if you are averse to doing your weekly checks!