The Z4, in contrast, will never be mistaken for anything other than a Z4. Even though BMW designers toned down Chris Bangle's controversial (but influential) flame surfacing for the current generation, the Z4's styling remains polarizing. Some, including design editor Robert Cumberford, think it's exceptional. Others, including this humble writer, still find it a bit overwrought. That impression is enhanced by our model's M aerodynamics package, which adds aggressive rocker and fascia extensions.
Both cars maintain a high level of style in their cabins. The SLK's interior here again borrows successfully from the SLS to great effect. Though we actually find the switchgear and details a bit pedestrian in the $183,000 Gullwing, it's more than enough to impress on a $66,805 SLK. In fact, the materials quality edges out that of the Z4, which as equipped is $64,225, although we still fancy the BMW's unique layout and circular secondary controls.
When it comes to more functional aspects of design, neither car avoids hardtop compromises completely. To lower the top - a process that takes about twenty seconds in either car - you need to first slide in place a trunk divider that slashes cargo room from 10.9 to 6.4 cubic feet in the Z4 and from a slightly better 11.8 to 7.9-cubic feet in the SLK. With the top up, however, the Mercedes scores a clear victory thanks to its general quietness - the Z4 rattles some over bumps - and a new parlor trick called Magic Sky Control. Introduced last year on the outgoing SLK, the optional panoramic sunroof automatically adjusts its tint level to let in just the right amount of sun. We won't go so far as to say we'd part with $2500 of our own money for the option, but on this test car it certainly relieved the cramped, dank atmosphere common to convertibles when the top is up.
Sweet six-cylinder sound, sour SLK seven-speed shifting
The engine downsizing zeitgeist will soon catch up with these roadsters - Mercedes and BMW will each introduce 2.0-liter four-cylinder variants within the next twelve months. For this fleeting moment though, power still rules and both these test cars produce lots of it. The "350" nomenclature for the SLK refers to a heartier version of the new, direct-injected 3.5-liter V-6 in the C-class, good for 302 hp and 273 lb-ft of torque. The sDrive35is muster even more. BMW's familiar 3.0-liter turbocharged inline-six here is tuned to deliver the same 335 hp and 369 lb-ft of torque as the 1-series M.