The last years of the SL55 AMG will be future collectibles. 55 Engine is a darling engine among the Mercedes Cogniscenti. It's a highly reliable engine, built from the "M113" block with a supercharger added, it's an engine that will be reliable for many years and kilometers. The M113 and M113K (the M113K means supercharged version) are known to be the most reliable engines Mercedes-Benz ever built; they are not extremely complex, SOHC, not too much fancy mechanical technology, and yet still create modern power. The 6.2 liter M156 engine had many reliability problems later in their lives, especially with broken headbolts that would leak coolant into the engine causing it to mix with the oil. This would water-lock the engine, destroying the entire engine.
I highly recommend a Mercedes-Benz with this M113 or M113K engine. It's a great piece of Mercedes-Benz history, as it stands for reliability. I'm currently looking for a 2001/2002 Mercedes-Benz E55 with the M113 engine, and I already own a vehicle with the M113K engine.