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The Mercedes-Benz SLR McLaren is a Anglo-German sports car jointly developed by Mercedes-Benz and McLaren Automotive. Built in Portsmouth and the McLaren Technology Centre in Woking, Surrey, England. Daimler AG, owner of Mercedes-Benz, also owns 40% of the McLaren Group.
Classified as a sports car and compared to cars like the Porsche Carrera GT and Enzo Ferrari, the presence of the automatic gear box, front mid-engined arrangement and its driving characteristics lead some commentators to classify the SLR McLaren as a Super GT whose closer rivals are the Aston Martin V12 Vanquish and Ferrari 599 GTB. One of the goals of the SLR was to combine both sports car and GT characteristics.[1]
It is the fastest automatic transmission car in the world. SLR stands for "Sport, Leicht, Rennsport" (sport, light, racing). Mercedes-Benz has stated that they will build 3500 SLRs in a span of 7 years, with an annual production of only 500 cars.[2] The car's base price is GB£300,000 (approx. US$495,000 or €475,000, c. 2007).[3]
History
The Mercedes-Benz SLR McLaren is inspired by the Mercedes-Benz 300 SLR of 1955 which was actually based on the W196 F1 car, yet named after the road-going 300SL Gullwing.
Brakes
The SLR McLaren can reach a speed of 210 mph and has a brake speed of 210 to 0 in 94.3 feet.The brake discs are carbon-ceramic which provide better stopping power and fade resistance than steel discs. Mercedes-Benz claims these discs are fade (wear) resistant to 1200°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 integral air brake flap. The spoiler increases downforce depending on its angle of elevation (angle of attack). At speeds above 95 km/h the spoiler/brake automatically raises to 10 degrees (15 in 722 edition), when demanded via the driver's switch, the elevation can be increased to 30 degrees (35 in 722 version) for increased rear downforce, at the cost of increased steady state drag. A final function is the automatic air brake, when engaged the rear elevation angle is increased to 65 degrees. The additional rear downforce in addition to the markedly increased aerodynamic drag increases peak deceleration ~25%.
Engine
The SLR sports a 232-kilogram (512 lb), hand-built, 5.4-litre (5439 cc/331.9 cu in), supercharged, all-aluminum, SOHC V8 engine. The cylinders are angled at 90 degrees with three valves per cylinder and lubricated via a dry sump system. The compression ratio is 8.8:1 and the bore and stroke is 97 millimetre (3.82 in) and 92 millimeters (3.62 in), respectively. The Lysholm-type twin-screw supercharger produces 0.9 bar (13 psi) of boost, the turbine rotates at 23000 revolutions per minute, and the air is cooled via two intercoolers. The engine generates a maximum power of 626 PS (617 hp/460 kW) at 6500 revolutions per minute and a maximum torque of 780 newton-metres (575 ft·lbf) at 3250 revolutions per minute. 2003 models were leaving showrooms at 616bhp and now are every so slightly increased to 626hbp (464kw).
Unlike most of its contemporaries, its engine is front-mid mounted. McLaren took the original concept car designed by Mercedes and moved the engine 1 metre behind the front bumper, and around 50 cm behind the front axle. They also optimized the design of the center firewall.
Performance
McLaren's performance claims for the SLR have been confirmed. Depending on the source, the car accelerates from 0 to 100 km/h in approximately 3.5 seconds (see below), 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 (208 mph), and has once reached a speed of 210 mph (340 km/h), which makes it the fastest car with a true automatic transmission with a torque converter. The car uses carbon fibre for its entire body construction, which makes it lighter. Curb weight is 1768 kg (3898 lb). The SLR is one of the safest and most luxurious cars of its class ever built, straying from the practice of eliminating luxuries for the sake of weight reduction.
Car and Driver achieved a 0-60 time of 3.6 seconds, and a quarter-mile time of 11.6 seconds at 125 mph (201 km/h). C&D suggests the times may be even lower if temperatures were higher. Car and Driver achieved 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.
Road and Track tested the car in their July 2005 Road Test and reached 60 mph (100 km/h) from a standstill in 3.5 seconds. The 0-100 mph sprint was achieved in 7.5 seconds and a Quarter Mile run was completed in 11.5 seconds at 126 mph (203 km/h).
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. They also reached its claimed 334 km/h top speed.
Comparison
Despite its 2-ton weight, the fuel economy is generally better than the lighter Lamborghini Murciélago, and even its lighter, less expensive, less powerful sibling, Gallardo.[4] Also, BBC auto show Top Gear put the SLR 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 [1]). However, on a separate race around the same track, the SLR was fractionally quicker than the Carrera GT. In a straight line, the SLR is quicker throughout the range.
722 Edition
A new version was introduced in 2006 called the Mercedes-Benz SLR McLaren 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" boosts power to 478 kW (650 hp) and 820 N·m (605 ft·lbf) torque at 4000 rpm, posting a top speed of 340 km/h (6 km/h faster than the standard SLR). 19-inch light-alloy wheels were used to reduce unsprung weight, while 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.[5]
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 0-300 km/h in 28 seconds. Exterior changes, other than the larger 19-inch black light-alloy wheels, include red 722 badging, hearkening back to the original 722 racer.
Roadster
A roadster version of the SLR has also been confirmed, due to go on sale in September 2007 for £350,000 ($711,065 U.S.). It uses the same supercharged V8 AMG power plant as its coupé siblings, developing 626 bhp (467 kW), to propel it to a top speed of 332 km/h and enable a 0-62 mph (0-100 km/h) dash time of 3.8 seconds. However, being a convertible the roadster will have to be burdened with extra weight and this will affect performance and handling. The Roadster's roof, however, is made from a "newly developed material" and hence will not take the form of a folding metal arrangement, as is now common on many modern cars. Following a manual unlatching, it takes a mere 10 seconds to fold away electrically. According to an official document from Mercedes, the cabin of the roadster is capable of allowing conversation between driver and passenger up to a speed of 124 mph (200 km/h) with the roof retracted. It is unsure if McLaren will release another version of the roadster like it did with the SLR 722 version. This roadster is aimed to compete against other sports cars such as the Pagani Zonda F Roadster.[6]
722 GT
The 722 GT is a tuned version of the SLR 722 which is developed for a one-make racing series. The cars are built by Ray Mallock Ltd. with approval from Mercedes-Benz. The car features new wider bodywork to accommodate 19 inch OZ racing wheels. The front grill vents are removed and larger, freer flowing air extractors sit on the hood and flank the side of the car. The rear now has a racing wing and diffuser.
Under the body, the car has shed 300 kg and reduced its dry weight to 1300 kg (2866 lb). The engine remains in relatively stock specification but now produces 500 kW (680 bhp) and 830 N·m (612 ft·lbf) at 1.75 bar (175 kPa) boost. Inside, the car is stripped out with only the essential functions being controlled from a carbon fiber binnacle. New carbon fiber door panels and full roll cage complete the transformation. Only 21 examples of the 722 GT are planned to be made, all of which will be for racing use only. Each costs upward of €750,000.
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