With the introduction of a four-cylinder model (actually late in the 2012 model year), the SLK Class now has a full lineup of versions, with a choice between four-, six-, and eight-cylinder engines.
Base four-cylinder versions get a 201-horsepower, 1.8-liter four, offered with either a six-speed manual or seven-speed automatic transmission. While we haven't driven the SLK with this engine, we've noted in the C250 Coupe that it provides perky, economical performance, with plenty of mid-range torque on tap and little, if no, turbo lag.
Most people will likely skip that, though, and go for the strong 302-horsepower 3.5-liter V-6--only available with the seven-speed automatic. A grunter, this V-6 has a typical tenor that either dazzles you or leaves you wanting for a straight six-- or best of all, a flat one. Mercedes posts a 0-60 mph time of 5.4 seconds and limits the SLK 350 to a top speed of 155 mph. That puts it solidly on the same playing field as the Porsche Boxster and BMW Z4, though there's not quite the same emotional appeal, either in its exhaust note or in its communication to the steering wheel and the driver's seat. You'll leave the SLK 350 in its Sport mode most of the time, since it wakes up the tranny with the smoothest blend of fast gear changes. In Eco mode the shifts are long and syrupy.
While we suspect the SLK 250 it probably the more balanced pick, the V-6's gusto pushes the SLK's multi-link suspension to its limits with a sharper feel than in the prior version. The SLK 350 can be outfitted either with either a conventional independent suspension or with user-selectable shocks, and all versions have electrohydraulic steering with Direct Steer, which amplifies steering inputs according to the rotation angle of the steering wheel. The hybrid steering system leaves the usual Mercedes play of an inch or so on center for a more relaxed attitude on the highway, and works its way into aggression by the time you're a quarter-past in either direction.
Go for the Dynamic Handling package, and the adjustable shocks make the SLK more tossable than it's ever been. While the SLK has been known in past iterations to have some bite, this SLK breaks loose softly and gradually, where it's easily brought back on line. Deep potholes still can jar, though. The deeply talented torque-vectoring brakes can clamp onto an inside rotor automatically to tighten cornering lines, and make the 18-inch, 35-series rear tires pretty obedient.
If you want brute force more than anything else, head straight for the SLK 55, which is stuffed to the gills with a 5.5-liter V-8. With 415 hp, this top dog sends its intentions reverberating through its mean-sounding exhaust. It's capable of 0-60 mph times of under 5.0 seconds, and it sounds like it. Tightened and screwed down even more, the SLK 55 still has a pervasive firmness to the ride, but its shocks have been tuned to demand less from the driver and more from the car--a much better balance for top-down cruising. In this version, you'll get a crisper transmission--the seven-speed Speedshift clutched automatic--and it's a willing partner especially in manual modes, with its large shift paddles and quick response. It's less graceful, but brilliant in its own right.