I had a 2003 ZHP, leased in May of 2003. It was my first BMW and I foolishly didn't grasp how special that car was until I picked up my 2006 e90 in Munich.
So since then I've been through many cars (including a few BMWs) and I keep coming back to how much I loved the ZHP. Turning that car on made me smile. No car since has come close.
My current car is on lease for another 17 months but I figure it's best to keep my eyes open and decide if I'm willing to buy a fairly old car just to recapture that sensation of ultimate car-driving bliss only my old ZHP provided.