So I bought a 2004 Z4 with 17K miles on it a moth ago. Drove it from Pittsburgh to Chicago to get it home and it was a blast! Wow! This car is comfy, roomy, powerful, reliable, and fun! The 2.5 has quite the power and I can't really notice a difference vs. the 3.0. What more can you ask for? The prices are very competitive these days for a pre-owned. I test drove a Z3 10 years ago and hated it so I bought a MR2 Spyder. This vehicle tops them both by far. Fairly quiet with the top up, especially for a convertible. and you can't really feel the wind too bad when its down.
Styling, safety features, gas mileage, trunk space, comfort for a sports car.