[mosta]

I don't know, you're the pro, so maybe I'm wrong, but in my limited experience used BMWs (and I'd assume Mercedes) can go forever, like well over 100k miles. they're more expensive to repair, but it's not like a ferrari or anything absurd.

but with regard to the M3 OP mentions, again I'm far from an expert, but I've seen too many stories about nightmare used M-series. sports cars attract abuse, and a lot of people want to modify them in all sorts of ways. I shy away from used sports cars, and the M-series qualifies, unless I hvae a really good source.