The 2008 SLK was the mid-cycle facelift for the 2004 generation, but in terms of refinement it had some important improvements.
Mercedes-Benz engineers had redeveloped around 650 components. On the outside, the most striking improvement was on the front bumper. It features a lower splitter inspired by Formula 1 race-cars. The now larger exterior mirrors feature LED indicators with a pronounced arrow shape.

The designers also modified the rear end by introducing a diffuser-style lower section that made the roadster appear more powerful when viewed from behind. The effect was enhanced considerably by the trapezoidal exhaust tailpipes and the AMG-style darkened taillights.

Inside, the 2008 SLK featured the NTG 2.5 audio and telematics generation for the first time. It was easier to operate and offered an even wider range of useful functions. Standard features integrated in every radio included a hands-free system with Bluetooth technology and a new media interface in the glove compartment, allowing the full integration of mobile audio devices such as an iPod. Together with the new telematics generation, Mercedes-Benz offered the LINGUATRONIC voice-operated control system as an optional extra in the SLK-Class for the first time.

Under the hood, the 3.5-liter V6 engine was upgraded and received 33 hp more, reaching 305 hp now. Also, the 200 Kompressor unit has been boosted by 21 hp, up to 184 hp.