Ralph, read the attached thread..
Who's the oldest hippo of them all?
Both Tinytdi and myself are running 150k( within 800 miles, in my case) Xedi's, and we're not the only ones..As for reliability, G13's got it smack on. Truth, mine has a few bits not playing, see my signature, but to be honest, for a 9 year old motor no probs. Tay's also right, the TD4 is a more refined, more powerful lump, but it can
have its share of probs too, as you will find if you peruse the posts here, also the posts on Beemer forums as regards desisel lumps. Bottom line is, get one thats bin serviced smack on interval, FSH and generally bin well cared for.
IMHO with a bit of fettling/tweakin and RoverRon's help & guidance, the L series can punch out more power than a TD4. Go for it Son!
Just re-read yer post, 80k is baby miles, just make sure the service book is stamped or you got receipts fer services. Check the back tyres out fer castelation(do a search on that one), and if yer find owt yer not sure on, post it up on here........
Re-read again( me eyes are wonky after a busy night shift....3am shouts again!) Full dealer service history speaks volumes...