RENNTech SLR7.4: Tested 0-150-0 MPH

From the August 1998 issue of Car and Driver.RENNTech SLR7.4Street Drivability: 5 stars
Durability: 5 stars
0 to 60: 3.7 sec, 183 ft
0 to 100: 8.7 sec, 775 ft
1/4-mile: 12.1 sec @ 119 mph
0 to 150: 20.9 sec, 3264 ft
150-to-0-mph braking: 691 ft
Total time, 0 to 150 to 0 mph: 28.3 secAny Car and Driver super-speedfest would be incomplete without one of Hartmut Feyhl’s German jato sleds. Feyhl, formerly of super-tuner AMG in Germany and now owner of Florida-based RENNTech Performance Tuning, raises the modification of Mercedes-Benzes to a high art form. His cars are blindingly fast, rock-solid reliable, and aesthetically exquisite. They are aristocratic hot rods.We tested this SLR7.4 when it was fresh out of open-engine surgery in March 1997. The operation bored and stroked the V-12 from its original 6.0 liters to 7.4 and greatly enhanced its ability to breathe, with an enlarged and polished intake manifold and bigger valves. The engine mods are worth $50,000 and are warranted for two years. A mellifluous high-flow RENNTech exhaust adds 10 grand. Another $5000 beefs up the transmission and adds a super-duty radiator and auxiliary coolers for the engine oil and transmission fluid. The bottom line: 585 hp at 6000 rpm; 601 pound-feet at 4000 rpm (up from 389 and 420). A $10,000 Torsen differential with a 2.82:1 ratio ensures equitable distribution of that immense torque.Those mods, plus a reduction in curb weight of nearly 400 pounds, take care of getting to 150 mph. All the driver must do is brake-torque to just off idle, say, 1500 revs, and then coax the throttle down. Easy does it, or those giant 295/35ZR-18 Pirellis will vaporize. Zero to 60 takes 3.7 seconds. Precisely. Run after run. Times to 150 mph varied by less than a second over four runs. Such rare repeatability speaks to the precision craftsmanship that is RENNTech’ s hallmark, earning the SLR7.4 a perfect score for durability.A glance at the time-to-speed graph shows that the SLR7.4 and the SVSi Viper are within a plotter pen’s width all the way to 150 mph, despite the SLR7.4’s slight power-to-weight deficit and power-sapping automatic transmission. Decelerating power comes from huge Alcon brakes. Six-piston calipers clamp 14.5-inch-diameter rotors in front, and four-piston calipers grasp stock 12.6-inch rotors in back. They make a powerful whoa! Despite being the heaviest car in this test, the SLR7.4 stopped in the shortest distance—just 691 feet from 150 mph to 0, 29 feet better than the second-place Corvette. In daily driving, the brakes feel grabby at low speeds, but they’re reassuring at highway velocities. In this superb car, they seem worth the $10,000.Ride comfort and drivability were high priorities, so when the stock adaptive-damping suspension was ditched in favor of custom springs, anti-roll bars, and Koni shocks, their settings were chosen carefully to preserve the poise of the donor SL. The result is a firm but never jarring ride, and the car changes direction much more quickly and crisply than does a stock SL600. For drivability, we gave the RENNTech the maximum five stars.But the aesthetic delights, which account for most of the remaining $115,000 worth of modifications, are what make the SLR so special. The top fabric is woven of dark green and beige threads to match the interior and exterior. The O•Z Magnesio wheels are finished in a coordinated beige color. The gauge cluster was reconfigured with the tach in the center and custom faces—beige, of course. Carbon fiber covers what used to be wood surfaces. Custom two-tone leather covers everything else, including a Passport radar detector.It’s ludicrously expensive, but it’s so close to perfection that it almost seems a bargain.RENNTech Performance Tuning; www.renntechmercedes.com
Source: caranddriver.com