I purchased a 2003 certified Diamond Silver SL55 avoiding the $50K depreciation. What a car. Incredible looks and power, and a great sounding rumble. The car is truely amazing, yet the navigation is dated years compared to Lexus. I have no regrets in the first 2,000 miles. I have heard both positive and negative reviews for the car so I purchased the extended warranty to 100K miles. It appears to be hit or miss with some of the cars with the research I've done.
The pure launch power is very impressive as well as the exhaust notes that follow, The top drops in seconds, it is the best looking hardtop convertable on the market. I've found that people clearly know the difference between the SL500 and SL55. They always stop to ask about it.
Upgrade the navigation system to a DVD based system and move the CD changer up front.