The SLK55 AMG has to be one of the best values in a sports car. Considering that most used 05-08 SLK55's are under $30K, that is an unbelievable value considering the technology, performance and amenities if offers.
Mine is getting up there in mileage, but the performance and engine are rock solid, reliable and I've had no issues whatsoever.
I really can't think of another car in this price range that turns as many heads, is as much fun to drive and feels as nice as this car.
This could be your only car - it's plenty comfortable, and spacious if you're not carrying cargo much. Fuel mileage is pretty bad, but worth it for the great performance.
Without a doubt - the engine is what the AMG line is all about. The 5.5 liter engine in a car this size is a monster. It's thirsty (I average 16 mpg with heavy driving), but the power curve is incredible.
The 7-speed transmission is excellent too - easy to use in auto mode, and has two different selectable manual modes (with paddle shifters).
The styling still looks fresh and updated even though the car is 6 years old now. And, the car looks great with top up or down -- rare for any convertible.
The interior is understated and simple, which suits the car perfectly. Comfortable bucket seats (airscarf is great!), nav is nice and large. Interior layout is excellent.
What a lot of these earlier reviews here don't mention (since their cars were much newer) is that when these SLKs get older, they develop tons of rattles, sqeaks, creaks and other noises regarding the convertible top. I can't even describe how loud and annoying they are, but they can be adjusted or eliminated at the dealership. Overall, it makes the car feel cheap, which is the antithesis of everything MB is about.
My favorite solution to that is simply putting the top down.
Other than that, and weak gas mileage, I have little complaints about this car. It's a great sports car that is worth every penny!