No regrets! My 2003 2.5i has been a pleasure to own and drive for the past two years. The car remains tight without squeeks and remains trouble free! The manual top can be lowered or raised quickly and easliy with only one hand and glass in the rear window is nice - but why should you care because the top will always be down.
Tight curves and sunny days. Unlike my friend's 2003 Boxster S, thus far the Z4 has held it's resale quit well.
An optional spare with non run-flats; disc pads that produce less brake dust; an alarm with movement sensors, the CD changer should have been mounted in the trunk to free up the limited interior storage.