We traded in a baseline model 2003 Porsche Boxster for this 2012 BMW Z4. Everything about the Z4 blows away the older model Boxster except handling. While the Z4 is still stellar on hard turns due to its Sport and Sport+ suspension modes, it weighs 500 lbs more than the Boxster and feels like it'll fishtail if you don't have excellent control of the accelerator. The Boxster felt like it was pulling you around corners. The Z4 makes you have to pull it around corners. Subtle distinction, but noticeable. Definitely don't regret the trade in though. It's faster than most muscle cars off the line (not a new Stingray though). 0-40 mph before you can blink, and the auto- and paddle-shifting are FAR faster and smoother than you could ever possibly do with a manual transmission. I've owned Mustang 5.0s that weren't this fast off the line, including a Shelby GT. The looks, sound, power, and technology of the Z4 are phenomenal. Just don't get in a wreck with it, you won't win.
I have had my 2012 Z4 for 4 years and 60k miles. No mechanic issues. Great MPG and it is a Rocket. I get compliments every time I fuel up. I had a Lexus, SC430 for 5 years before this car. The Lexus was great but this is Great plus gets a whole lot more attention. I love it. This is my 4th BMW. They just make great cars. I had a Z3 before the Lexus and put 230k Miles on it before selling it to my neighbor who still drives it as a weekend car.