Late last year Mercedes-Benz introduced a turbocharged four-cylinder version of the SLK--the SLK 250--and it's the model to get if you like the SLK's style, luxury, and features but want good gas mileage. EPA ratings for this model range up to 23 mpg city, 33 highway, with the seven-speed automatic transmission.
Otherwise, the mid-level SLK 350 delivers good fuel economy, considering the performance that it delivers. The SLK 350 earns an EPA-rated 20/29 mpg, thanks to its small size and its standard seven-speed automatic. These models for 2013 now get start/stop technology that automatically stops the engine at stoplights, in some conditions, and restarts it when you lift back off the brake.
The SLK55, on the other hand, is a different beast altogether; but with EPA ratings of 19 mpg city, 28 highway, it's better than you might think--thanks in part to cylinder-deactivation technology that shuts off fuel to four of the eight cylinders under light running loads.