Mercedes Benz SL55 AMG vs. Audi RS4
The SL500 was the top-selling version of the SL-Class early in the R230 series. It used a 5.0 L V8 engine, which produced 306 hp (228 kW) and 339 ft•lbf (460 N•m).
A 5.5 L 32-valve V8 engine replaced the 5.0 L found in the SL500 for 2007. The engine is essentially the old SL55 engine without the addition of supercharger. The 5.5 litre natrually aspirated V8 can also be found in the new SLK 55 AMG. This model will retain the SL500 name in most markets, but will be sold as the SL550 in North America. It now produces 382 hp (285 kW) and 391 ft•lbf (530 N•m). It now accelerates from 0-60 mph in 5.3 seconds and has a limited top speed of 155 mph (249 km/h).
In 2007, Mercedes will create 75 limited-edition 50th Anniversary SL550s. According to another article, Mercedes created 550 of these cars, all pewter in color with burgundy leather, black ash wood trim, 18-inch double five-spoked wheels, and matching 50th Anniversary Edition luggage.
The SL600 is the highest-output version of the non-AMG SL-Class models. It uses a V12 engine which produced 493 hp (368 kW) and 590 ft•lbf (800 N•m) from 2003 through 2006 and was uprated to 510 hp (380 kW) and 612 ft•lbf (830 N•m) for 2007. It accelerates from 0-60 mph in 4.7 seconds, according to Mercedes-Benz. However Car and Driver achieved extremely impressive acceleration test figures with 60 mph (97 km/h) achieved in just 3.6 seconds, 100 mph (160 km/h) in 8.6 seconds and a Quarter Mile run in 11.9 seconds at 120 mph (190 km/h).
The SL55 AMG version was released in 2002 with a supercharged 5.4 Liter, 5439 cc Mercedes-AMG V8 engine. This produced 493 hp (368 kW) at 6,100 rpm and can propel the car to 60 mph (97 km/h) in 4.7 seconds, according to Mercedes-Benz. Car and Driver got 60 and 100 mph (160 km/h) in 4.5 seconds and 10.9 seconds, respectively. The car completed the Quarter Mile in 13 seconds flat at 110 mph (180 km/h).
The SL55 AMG was updated for 2007 with a 510 hp (380 kW), 531 ft•lbf (720 N•m) version of the same engine. With increased power and torque, the car can now, according to the official website, accelerate to 60 mph (97 km/h) in 4.4 seconds, 0.3 seconds quicker than before. The new model has only slight visual differentiators, the most noticeable is the three-slat grille rather than the four-slat version used previously. The top speed is limited to 155 mph (249 km/h), but can be extended to 186 mph (299 km/h) for an additional cost. The 6.3 liter V8 is expected to replace the current engine for the 2009 model year. Upon release in 2002 this was for it’s time the fastest automatic car in the world. Of course this was before the SLR Mclaren hit the market in 2003-present.