Started with a 2.3 Z3, moved to 3.0 Z3 and now 3.0si Z4. This is the best one so far. Took me a few years to warm to the styling but now suddenly it clicked. The chassis is exceptionally stiff - as stiff as the Z3 coupe was. Makes a huge difference. The car feels of one piece and there are no rattles or creaks. Huge storage space in the trunk (for a 2 seater), excellent gas mileage, very powerful engine. A pleasure to drive.
Hill holder. This feature needs to be standard in all manuals. It's THE feature that helped my wife get comfortable with driving a stick-shift. Now she loves to drive the car. The one-touch button for top operation is great. Fast and easy. Glass rear window. Extended leather!
Make 17" wheels an option with sport package. Make RFTs optional as well. Reverse mirror tilt should be a part of the package.