Started with a 2006 Z4, 2.0i, p/ex that for a 1999 Z3 2.8i 1 owner and just 25k miles. Significant other has just bought a 2009 E89 2.3i auto, again 1 owner from new with only 20k.
The Z3 is the garage queen, we will do less than 1k miles per annum. The E89 is a lovely car to drive, my missus does about 4K per annum.
We have a 2010 523i touring which is the work horse. Picked it up almost a year ago, 1 owner with 32k miles, it now has 58k