Nuts and Bolts The EPA suggests that, when equipped with the manual transmission, the SLK350 should return 18 mpg in the city, 25 mpg on the highway, and 21 mpg in mixed driving. All other SLK-Class models are expected to return 16/22/18 mpg, respectively. Our tester, a SLK350 with a six-speed manual, achieved only 17.9 mpg in mixed driving.

Regardless of whether it’s the 350 or 55 AMG, buyers of the 2005 Mercedes-Benz SLK-Class roadster will be rewarded with an abundance of power, a taut suspension, and aggressive brakes.

The 2005 SLK350 is powered by an all-aluminum, 3.5-liter, dual overhead cam, 24-valve V6 that puts out 268 horsepower at 6,000 rpm and 258 lb.-ft. of torque at 2,400 rpm. Managing that power is a six-speed manual transmission, though a seven-speed adaptive automatic transmission with a manual mode is optional. The EPA suggests that, when equipped with the manual transmission, the SLK350 should return 18 mpg in the city, 25 mpg on the highway, and 21 mpg in mixed driving. Swap in the automatic transmission and those ratings drop to 16 mpg in the city, 22 mpg on the highway, and 18 mpg in mixed driving. Over the course of several hundred miles on the streets, highways, and back roads of southern California, our six-speed test car achieved only 17.9 mpg. Premium fuel is required.

Surprisingly, a move up to the 355-horsepower 2005 Mercedes-Benz SLK55 AMG, available only with a seven-speed, SpeedShift automatic transmission, garners the same EPA results as the automatic-equipped V6. However, all that horsepower is surely hard to ignore, something that would ultimately prove harmful to real-world fuel efficiency. Ponying up the power is an all-aluminum, 5.5-liter, single overhead cam, 24-valve V8 that reaches peak horsepower at 5,750 rpm and provides 376 lb.-ft. of torque at 4,000 rpm.

A fully-independent, multi-link suspension allows the bounty of engine power to be used in the twisties as well as on the straight-aways. The front suspension uses MacPherson struts, and stabilizer bars are bolted on front and rear. The 2005 model ushers in the use of MacPherson struts as part of the front suspension, replacing the double wishbone setup used in the previous generation SLK. Stopping power for the SLK350 is provided via 330-mm ventilated discs up front and 290-mm solid discs in the rear; the SLK55 AMG features 340-mm ventilated front discs and 330-mm ventilated discs out back. Both SLK-Class models come with antilock brakes, electronic brake assistance, traction control, and stability control. Connecting all the hardware to the road are high performance tires. The SLK350’s 17-inch wheels are shod in 225/45R17 Pirelli P Zero tires up front and 245/40R17s on the rear; the SLK55 AMG wraps its 18-inch wheels in 225/40R18 tires up front and the rears get 245/35R18 tires.