Mercedes SLR

The Mercedes-Benz SLR McLaren is a sports car and supercar automobile co-developed by DaimlerChrysler and McLaren Cars. It is the fastest automatic transmission car in the world. It is assembled at the McLaren Technology Centre in Woking, England. Most people presume "SLR" to stand for "Sportlich, Leicht, Rennsport" (German for "Sport; Light; Racing"), while it actually means "super-leicht, Rennsport" (super-light, racing). The car's base price is €443,066 £300,000 or $450,000 (see today's $/£/€ parity) .

A new version was introduced in 2006 called the "2007 Mercedes-Benz SLR 722 Edition". The "722" refers to the victory by Stirling Moss and his co-driver Denis Jenkinson in a Mercedes-Benz 300 SLR with the starting number 722 (indicating a start time of 7:22 a.m.) at the Mille Miglia in 1955. The "722 Edition" creates 650 bhp, with a top speed of 337 km/h (3 more than the standard SLR). Countering the problems from the previous, a new suspension is used with 19-inch light-alloy wheels, a stiffer damper configuration and 0.4 inches lower body. The SLR is planned to end production in 2008, according to Mercedes-Benz.

The Mercedes McLaren SLR is inspired by the Mercedes-Benz 300 SLR of 1955. This sports car racer was actually based on the W196 F1 car, yet named after the road-going Mercedes 300SL Gullwing. A notable feature of the SLR is its gullwing doors, a homage to the original 300 SLR.

Engine

The SLR has a supercharged 5.5 (5439 cc) litre dry sumped 90 degree V8. It produces 466.8 kW at 6500 rpm (626 hp) and 780 N·m (575 ft·lbf) torque at 3250 - 5000 rpm. AMG technicians took the original SL-55 AMG engine and optimized its capacities by enlarging the fuel pump, the cylinders, and put a larger cooling system that absorbs air to cool down the engine. It has 3 valves per cylinder with SOHC. This is very unusual as most supercars, indeed most modern cars, have DOHC and 4 valves per cylinder, but it keeps with the recent trend in modular V engines from Mercedes Benz and decreases engine emissions. The Twin-screw type supercharger and the 2 aluminium rotors have a maximum speed of 23,000 rpm. It is mounted between the two engine banks and uses 120 bhp at maximum capacity.

Unlike most of its contemporaries, its engine is front-mid mounted. McLaren took the original concept car designed by Mercedes and moved the engine fully 1metre behind the front bumper, and around 50 cm behind the front axle. They also optimised the design of the centre firewall.

Brakes

The brake discs are carbon-ceramic which provide better stopping power and fade resistance than steel discs. Mercedes-Benz claim these discs are fade resistant to 1000 °C. The front discs are internally vented and 370 mm in diameter. 8 piston calipers are used. Rear discs are 360 mm in diameter with 4 piston calipers. The result of these massive rotors is a maximum braking power of 1500 kW. When it is wet the calipers automatically skim the surface of the disks to keep them dry.

The SLR also has a spoiler mounted on the rear which pops up when braking from high speeds. The spoiler greatly increases drag at high speeds. See for a picture of the spoiler down and up (in use). This additional braking power on the order of 0.25 g of deceleration helps the car to stop quicker than any other car of its category.

The SLR has been criticised for its braking performance. While all agree that the brakes are extremely powerful, some critics argue they are either "on or off". Such critics include Top Gear's Jeremy Clarkson and Richard Hammond. In addition to this when the SLR is under braking extra fuel is pumped in to cool the engine. Since the exhausts are mounted in front of the driver's position the smell of unburnt fuel is noticed in the cabin.

Clarkson commented that "[The brakes] glow when you use them, and catch fire when you use them a lot". The brakes burn any debris on them and contrary to popular belief, the car itself does not catch on fire. This was proven during the 2006 Goodwood Festival of Speed when during the Supercar Run, Gary Paffett performed a huge burnout, only to have the brakes catching fire, though relatively small and could be seen around the rim as the car stood still.

Transmission

The SLR comes with a five speed automatic transmission with three separate modes: Sport, Comfort and Manual. Sport used for everyday use, Comfort starts in second gear for bumpy or slippery roads. Manual allows the driver to shift gears with the touchpad or the simple levers on the steering wheel. When in Manual, three additional modes (Sport, Supersport, Race) on the second dial can be used, each significantly making quicker shift times. This is the same transmission as used in other performance models such as the SL65 AMG. The Mercedes-Benz seven speed automatic transmission as used on the SLK 55 AMG cannot handle power and torque output of the SLR; hence it is fitted with only a five speed transmission.

The gear ratios are as follows: 3.56:1, 2.19:1, 1.41:1, 1.00:1, 0.831:1.

Performance

Mercedes-Benz claims that the car accelerates from 0 to 100 km/h in 3.8 seconds (0-60 mph in 3.4 seconds at 98 °F), 0-200 km/h in 10.6 seconds, and 300 km/h in 28.8 seconds, and has a top speed of 334 km/h (207 mph)[1] which makes it the fastest automatic, (although some consider the Bugatti Veyron to be the worlds fastest automatic car, it utilizes a dual clutch sequential manual transission and not a true automatic). The car uses carbon fibre for its body construction which makes it lighter. The car is, however still quite heavy at 1768 kg due to the numerous luxury items included in it. It has never reached a higher speed than 210 mph.

Car and Driver got a 0-60 time of 3.6 seconds, and a quarter-mile time of 11.6 seconds at 125 mph. These are during a test session that took place in the late afternoon, when October temperatures were on the decline. C&D suggests the times may be even lower if temperatures were higher. Car and Driver got top gear acceleration 30-50 mph and 50-70 mph times of 1.7 and 2.4 seconds, which are the fastest ever recorded by the magazine in a production car. The SLR also pulled 0.97 g on the skidpad.

The German magazine Auto Motor und Sport, in 2004, tested the SLR at the Nardo test track in southern Italy. They reported that the SLR accelerates from 0 to 100 km/h in 3.8 seconds, 200 km/h in 10.7 seconds, and 300 km/h in 30.6 seconds. The car's 400-meter time and 1 km time were found to be 11.5 seconds at 207 km/h, and 20.5 seconds at 269 km/h, respectively.

The most criticised parts of the car are its brakes. "It's not that they don't work—they do, but it's the way they do it: they are either on or off" (Richard Hammond, on Top Gear). Although extremely powerful, they are described as binary, as if they were made for panic stops at 200 mph.

Some critics suggest the better buy is a Mercedes-Benz SL65 AMG - a more planted car with a more powerful engine (738 lb-ft torque), for about $200,000 less. It accelerates 0-60 mph 0.1 seconds slower and has a top speed limited to 155 mph. . It can however have the speed limiter removed for a mere 800 dollars with a chip from Brabus or Renntech.

Not many cars are in the same league with the SLR. It's cheaper than an Enzo Ferrari by about $200,000, but costs about $10K more than a Porsche Carerra GT. It only costs half as much as a McLaren F1 did in 1997. The SLR can't touch the top speeds of the Enzo or the McLaren F1 (217 and 240 mph, respectively), but it beats the Carerra GT by two mph.
The Enzo and F1 also dwarf the SLR's horsepower, but the Carerra GT is more comparable, with only 604 hp to the SLR's 617. Perhaps the most telling difference is weight. The McLaren F1 is a slender 2,513 lbs., the Enzo weighs 3,020 lbs., and the Carerra GT weighs in at 3,043 lbs. The SLR, with its luxury interior, is a scale-busting 3,858 lbs.

Despite its 2-ton weight, the fuel economy is generally higher than the lighter Lamborghini Murcielago, and even its less expensive, lighter, and less powerful sibling, Gallardo. Also, BBC auto show Top Gear put this car and the Porsche Carrera GT on its track, and the Porsche beat the SLR-Mclaren by just over a second (1:19.8 vs. 1:20.9).

Special editions
722 Edition

A special edition known as the 722 Edition was released in 2006, to commemorate a previous Mercedes 'SLR', the 300 SLR. The 722 number is a reference to the race number of Denis Jenkinson and Stirling Moss's 1955 Mille Miglia winning 300 SLR, indicating their start time of 7.22 a.m.

Power is boosted to 478 kW (650 hp) and 820 N·m (605 ft·lbf) torque at 4000 rpm. Modifications were also made to the suspension, with a stiffer damper setup and 10 mm (0.4 in) lower ride height introduced for improved handling. Larger 390 mm diameter front brakes and a revised front air dam and rear diffuser were fitted.

Overall performance has increased, with a claimed 0-100 km/h time of 3.6 seconds, 0-200 km/h time of 10.2 seconds and 0-300km/h in 28 seconds.

Exterior changes included larger 19-inch black alloy wheels and red "722" badging (harking back to the original 722 racer).