For 1999, the SL500 is powered by a new 5.0-liter version of the new-generation 4.3-liter V8 introduced in the hot E430 and C43 models last year. Underneath the attractive plastic covers is a single overhead-cam engine that uses the Mercedes-Benz twin-spark, 3-valve-per-cylinder technology that reduces start-up emissions with no loss of horsepower compared to 4-valve designs. The post-combustion volume of exhaust is easily handled by the single exhaust valve. The two spark plugs can fire with a varied stagger-time difference between the two sparks -- depending on engine speed and load. As a result, the V-8 produces a peak output of 302 horsepower at 5600 rpm and a torque plateau of 339 foot-pounds from 2700 rpm to 4250 rpm. Maximum torque is less than before, but it makes the SL500 more responsive across the board and, per manufacturer's tests, significantly reduces the 0-60 mph acceleration to 6.1 seconds. It's cleaner too, certified as a California Low Emissions Vehicle and, according to Mercedes, is "performing at Ultra Low Emissions Vehicle levels." One can indulge him or herself without plundering the environment.

The SL500 has a fully independent suspension, with strut-type setup up front and a five-link design at the rear. It is abetted by the Mercedes-Benz Electronic Stability Program (ESP), which takes anti-lock braking and traction control one step further. ESP, standard on the SL500 this year, momentarily applies the brake on one wheel whenever understeer or oversteer is detected by a central computer using various motion and wheel speed sensors. (Understeer is when the front tires begin to lose grip; oversteer is when the rear tires begin to lose grip.)

The brakes are massive four-wheel discs, almost a foot in diameter up front and only an inch smaller in back. They are backed up with the Mercedes-Benz Brake Assist system. Hit the brake pedal fast and Brake Assist presumes a panic stop and applies full braking force faster than most drivers, reducing stopping distances in emergency situations. Standard tires have been upgraded to 245/45ZR17 on 8.25x17-inch wheels.

The new Sport Package adds to the sporty look of the SL with a special aerodynamic front bumper designed and installed by AMG, the famous tuner firm that specializes in Mercedes-Benz products. The bumper has projector beam fog lights in a deeper apron with a mesh air dam.

To further sharpen handling, the Sport Package includes unique 18-inch wheels fitted with extremely low-profile tires -- 245/40ZR-18 front and 275/35ZR-18 rear. In addition to their performance benefits, they look really great. Mercedes-Benz notes that the entire $4,970 Sport Package is priced lower than aftermarket wheels and tires alone and that everything is covered by the factory warranty. Suspension and steering calibrations are unchanged.

An alternative to the $82,695 SL500 is the $130,095 SL600, which is powered by a V12 that makes 389 horsepower. (Prices include $595 destination charge and Federal Gas Guzzler taxes - $1,000 for SL500, $2,600 for SL600.) The Sport Package is available for either model.