I traded my '04 Z4 2.5 on an SRT6. I have two friends that have Z4 3.0s and two that have Z3s. One is a 2.3 six and the other is an M Roadster.

The SRT6 blows them all away in just about every category. I always liked the looks of the Z3 and Z4 and would say the SRT looks as good as either of the other two. I get about the same number of comments on the SRT that I did on the Z4.

The Z4 2.5s go did not match its looks. While it always felt quick, about the only thing it would beat was standard econocars. It always felt quicker than it was. One problem area was the front lip. It hung down very low. I hit the curb more than once. It finally sheared off the plastic pins in the right fender well where the bumper cover and finderliner met. I had to use machine screws to hold it together (or I could have spent $500 for a new cover). Everyone I know that has a Z4 has either scraped up or broken the lower front of the bumper/lip.

Handling was excellent if a little light in the steering. The SRT steering is more firm and controlled. Braking was not as good as the SRT either (this includes the 3.0s). Requiring much longer to stop and feeling a little softer than the SRT.

The seating position of the Z4 was a little better with a wider cockpit and a lower door sill. One thing I did not like about the Z4 was the sound of the door closing. It really sounds tinny. Closing the door on the SRT sounds really solid. Although the cars weigh approximately the same, the SRT feels much more substantial. I have to admit though, the BMW straight six really is a work of art and probably the smoothest running engine I have ever driven.