I held off on all Mercedes until I saw the 2003 SL500, which I bought and enjoyed immensely. My only complaint was that I felt that for this level of car, and for it's weight, it was a little underpowered. I test drove the new SL550, which substantially improved the engine power problem with the improved torque and horsepower. I had the opportunity, however, to purchase a new 2006 SL65, and the difference is again night and day. I love the instant power without any significant turbo lag, and yet the elegant and sophisticated luxury package in which this beast is housed. Though much more subtle in appearance than some comparables, the car demands one's attention. Performance is superb.
Design. Hard top convertible feature is the finest. The power of the twin turbos, coupled with the huge ceramic brakes as well as the driving control systems gives excellent stability to this thoroughbred power plant.
My only thought for improvement would be more advanced electronic communication immediately available, that is, Voice control standard, and Bluetooth and compatibility with the majority of cell phones readily available.