The 2010 Mercedes-Benz SLK-Class comes in three models, each now with a very different driving personality. The SLK300's engine remains a 228-horsepower, 3.0-liter V-6-it's strictly for sun-worshipping folks with lower expectations for performance, though conversely, it's the only SLK that offers a six-speed manual transmission. Its 0-60 time is estimated at 6.1 seconds, with a top speed of 155 mph and 17/26 mpg fuel economy for the manual car, 19/26 mpg with the automatic. Edmunds claims even this base SLK300 "provides sprightly acceleration." Popular Mechanics thinks it's a "bummer" that the manual can only be had in the low-powered SLK, though.
The SLK350 runs around a 3.5-liter V-6 with 300 horsepower teamed to a seven-speed automatic. It's the mainstay of the lineup, with ample acceleration and a light snarl as it rises through its powerband. Benz pegs its 0-60 mph time at 5.3 seconds, top speed at 155 mph, and fuel economy at 18/26 mpg. The engine takes advantage of the SLK's quick handling response and good dynamic balance in tight corners. Car and Driver tested the prior version and "ran from 0 to 60 in 5.4 seconds"; they note the additional 32 horsepower "should knock a few 10ths off that time." Cars.com performed a road test of "about 150 miles of mostly highway driving," and they found that "the SLK350 averaged 29 mpg."
The fangs come out with the exclusive SLK55 AMG, with what Edmunds calls "a beastly 5.4-liter V8 that cranks out 355 hp and 376 lb-ft of torque." The power's shot out through its rear wheels via a seven-speed automatic, larger wheels and tires, a tightly controlled ride and handling, and breathtaking acceleration. While the seven-speed automatic can feel slow in the lesser SLKs, it's cured in the SLK55 AMG with the addition of paddle shifters and a SpeedShift transmission program. The estimated 0-60 mph time is 4.9 seconds, with a top speed of 155 mph and 14/22 mpg gas mileage. Car and Driver calls the seven-speed simply "excellent," while Cars.com also gives high marks for the "smooth shifts that can't be felt most of the time."
All SLKs benefit from a mechanical variable-steering gear that quickens the steering ratio in tighter corners and helps improve on-center tracking. Popular Mechanics says that "a new, all-mechanical direct-steer system tightens the steering ratio when the wheel is turned a mere 5 degrees off-center," which improves overall handling significantly when combined with the "speed-sensitive power assist." And though the suspension is tuned for little roll, the 2010 SLK roadsters each have a relatively smooth, composed ride. Kelley Blue Book contends that the "ride has definitely been improved," and Edmunds reports the 2010 Mercedes-Benz SLK-Class is "comfortable and compliant enough to appeal to the average driver." Cars.com declares with the improvements, the SLK "proves to be a decent touring car."