Although the innovative first-generation SLK was considered somewhat effeminate, the current SLK looks like a three quarter scale SL, which is a compliment. The SLK pioneered the retractable hardtop sports car, which adds an extra measure of quietness and security. Available engines include a 228-bhp 3.0L V-6, 300-bhp 3.5L V-6, or the 355-bhp supercharged 5.5L V-8 in the SLK55 AMG. Transmission choices are a 6-speed manual or 7-speed automatic. A vast option list allows customers to personalize their SLK; especially the "designo" packages, which combine interior and exterior trim with a color-coordinated theme.

The SLK receives a minor facelift featuring a restyled grille, new front and rear fascias, new side mirrors and taillights. The interior features a new steering wheel and head unit. The SLK300 model replaces the SLK280. On the SLK350, the output of the 3.5L V6 has been increased to 300 hp and 265 lb-ft of torque.