2002 Mercedes-Benz C32 & SLK32 Engine & Transmission Review

Mercedes-AMG starts with the same basic 3.2L V-6 found in many M-B models, including the C320 sedan and SLK320 roadster. The block and 3-valve/cylinder SOHC cylinder heads are retained. Many internal engine parts are swapped for stronger components, including the crankshaft, connecting rods, pistons, camshafts, oil pump, and valve springs. External upgrades include a high-flow low-back-pressure exhaust system, reprogrammed engine computer, and, of course, that belt-driven supercharger. As with AMG powerplants, one worker handbuilds each engine from start to finish-no assembly lines here.

The program's engineers had a big horsepower target, but were under orders to keep emissions levels and fuel consumption as low as possible. Therefore, they specified an extraordinary supercharger design, using Teflon-coated helical rotors. To help improve mileage and emissions compliance, AMG fitted an electromagnetic coupling to disengage the supercharger under low-load conditions, such as highway cruising or idling. But don't worry about lazy throttle response: The supercharger kicks in within milliseconds of an urgent throttle request, seamlessly pumping out 14.5 psi of boost. We spent several days driving C32s and SLK32s (plus the very cool C32 wagon we don't get here in the U.S.), and not once could we tell when the supercharger was generating boost or not. The power is right there, right now, when you need it.

A water-to-air intercooler sits between the cylinder banks and is connected to a separate front-mounted radiator; this device cools the intake charge for more power and less risk of detonation (pinging). The result is a huge power and torque increase over a stock C320: Horsepower climbs from 215 to 349 (a 62.5-percent improvement), and torque is advanced from 221 to 332 lb-ft (50 percent more). All this punch should translate into 0-60-mph times in the low 5-sec range for both cars, compared to 6.6 for the SLK320, 6.9 for the C320, and 5.8 for the C43. A further indicator of this engine's strength is that it has the same peak horsepower as the 5.5L V-8 that powers other AMG models, including S55, CLK55, and E55-AMG's sales-volume leader.

A newly developed five-speed automatic is the only transmission offered, and it's one of the best we've driven. Even though some will chastise Mercedes-AMG for not installing a manual gearbox in either car (you can get a manual in the SLK320 and C240), this seemingly negative attribute will be neutralized once you try the auto trans fitted with what the company calls SpeedShift. It features electronic controls that allow an aggressive downshift under hard braking, while upshifting is restricted during high lateral gs, so the car will hold its gear in hard cornering. This transmission also features 35-percent-quicker shift programming (compared to a C320) and a function that selects the optimum passing gear when the shift lever is held to the left. We'd be happier with a stick, but this unit will satisfy most everyone else.