E34 M5 3.8
Why? Brought a LHD 3.6 over from Germany about 15 years ago and loved it for the 2 years I had it. Bought it with 180k on in and sold it with over 220k. Not cheap to run but cost no more than 50k milers in terms of reliability and maintenance.
Loved the 3.8's I tried but was always scared off with the (quite common) risk of the adaptive suspension going wrong, seeing as this one's got the nurburg pack but had the suspension replaced and a brake upgrade which is possibly the only other weak area of the M5, it should make a pretty decently reliable daily.