I love my 928. I had a 944 in the 80's and it was nice but I am a V8 man. Just remember its a toy and an expensive one at that. My first year I bought it used (2009) (EBAY) every 2nd drive was to the shop lol. Every time another light comes on I wanted to dump it, but when its repaired I decide its too much fun to sell. Who needs money anyways. My mechanic tuned it up before I moved and whatever he did changed the mileage from 10 MPG to over 20. Yes that's right, cruising at 80 I an getting 22 MPG, not just by the computer results but by the miles I go between tuneups.
Drove one when I was 16, promised to get one someday... it took 20 years! Now that I have it, it is sooo awesome!!! So much power. Beats any exotic car of that era, but at a fraction of a cost due to its lack of appreciation from the Porsche purists. HPs are there, and it just sticks to the road. Still, being overengineered (and overpowered) this car is (mechanically) really reliable. Only problems I had were electrics. Window switch and lights. No major issues. Also, interior finish always is an issue with 928s. If you find one with a still good interior, just buy it!!! Definitely the more bangs for your buck!