Mercedes-Benz SLR McLaren

The Mercedes-Benz SLR McLaren is a grand tourer car jointly developed byMercedes-Benz and McLaren Automotive, built in Portsmouth and the McLaren Technology Centre in Woking, Surrey, England and sold from 2003 to 2010. When it was developed, German manufacturer Mercedes-Benz owned 40 percent of theMcLaren Group.

Due to the automatic gear box, front mid-engined arrangement, and its driving characteristics, some commentators classify the SLR McLaren as a GT, whose rivals would be vehicles such as the Aston Martin DBS V12 and Ferrari 599 GTB Fiorano.

SLR stands for "Sport Leicht Rennsport" (Sport Light Racing). Mercedes-Benz stated that they would build 3,500 SLRs over seven years, with an annual production of 500 cars.

History

he Mercedes-Benz SLR McLaren was inspired by the Mercedes-Benz 300 SLR Uhlenhaut Coupe & Racecar of 1955, which was a modified Mercedes-Benz W196 F1 race car. It was introduced on 17 November 2003. On 4 April 2008, Mercedes announced that they would cease production of the SLR. The last of the coupes rolled off the production line at the end of 2007 and the roadster version was discontinued in early 2008.

Technical highlights

Brakes

The SLR features Sensotronic, a type of brake-by-wire system. The brake discs are carbon-ceramic and provide better stopping power and fade resistance than steel discs when operating under ideal working temperature. Mercedes-Benz claims these discs are fade resistant to 1,200 °C (2,200 °F). The front discs are internally vented and 370 mm (15 in) diameter eight-piston callipers are used. Rear discs are 360 mm (14 in) in diameter with four-piston callipers. During wet conditions the callipers automatically skim the surface of the discs to keep them dry.To improve braking performance there is an automatic air brake, when engaged the rear elevation angle of the rear spoiler is set to 65 degrees.

Aerodynamics

The SLR features active aerodynamics; there is a spoiler mounted on the rear integral air brake flap. The spoiler increases downforce depending on its angle of elevation (angle of attack). At a set speed, the spoiler/brake automatically raises to 10 degrees (15 degrees in the 722 edition), when demanded via the driver's switch, the elevation can be increased to 30 degrees (35 degrees in the 722 version) for increased rear downforce, at the cost of increased steady state drag, also when the driver applies the brakes the spoiler raises.

Engine

The SLR sports a 232 kg (510 lb) hand-built 5,439 cc (5.439 L; 331.9 cu in), supercharged, all-aluminium, 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 mm × 92 mm (3.8 in × 3.6 in). The Lysholm-type twin-screw supercharger rotates at 23,000 rpm and produces 0.9 bar (13 psi) of boost. The compressed air is then cooled via two intercoolers. The engine generates a maximum power of 626 PS (460 kW; 617 hp) at 6,500 rpm and maximum torque of 780 N·m (580 lb·ft) at 3,250 to 5,000 rpm.The engine is front-mid mounted. McLaren took the original concept car designed by Mercedes and moved the engine 1 metre (39.4 in) behind the front bumper, and around 50 centimetres (19.7 in) behind the front axle. They also optimised the design of the centre firewall.

Transmission

The SLR uses AMG SPEEDSHIFT R five-speed automatic transmission with three manual modes. For durability Mercedes selected a five-speed transmission rather than their seven-speed gearbox which was more complex and used more parts.

Performance

The car uses carbon fibre reinforced plastics (CFRP) construction in an attempt to keep the weight low. Despite CFRP materials the total curb weight is 1,750 kg (3,858 lb).

Car and Driver achieved a 0 to 60 mph (97 km/h) time of 3.4 seconds, and a quarter-mile time of 11.2 seconds at 130 mph (210 km/h) C&D suggests the times may be even lower if temperatures were lower. Motor Trend tested the SLR and achieved a 0-60 mph time of 3.3 seconds in April 2006. 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 1.13 g on the skidpad.

Comparison

Despite its near 2-ton weight, the fuel economy is generally better than the lighter Lamborghini Murciélago, and its lighter, less expensive, less powerful sibling, Gallardo. Still, on the Episode 2 from Season 13 of BBC car show Top Gear the Lamborghini Murciélago LP670-4 SV performed a little slower than the SLR McLaren 722 Edition during a race special in Abu Dhabi although the Lamborghini weighed 1,565 kg (3,450 lb) and had about 20 PS (15 kW; 20 hp) more. Also, the same show put the SLR and the Porsche Carrera GT on its track, and after multiple attempts, the Porsche beat the SLR-McLaren by just over a second (1 minute 19.8 seconds compared with 1 minute 20.9 seconds). However, on a separate race around their short track, the SLR was fractionally quicker than the Carrera GT. In a straight line, the SLR is quicker after around 100 mph (160 km/h).

Variants

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" includes an engine rated 650 PS (480 kW; 640 hp) at 6,500 rpm and 820 N·m (600 lb·ft) at 4,000 rpm, with top speed of 337 km/h (209 mph) (3 km/h (1.9 mph) 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 (0.39 in) lower ride height introduced for improved handling. Larger 390 mm (15 in) diameter front brakes and a revised front air dam and rear diffuser were fitted.

Exterior changes, other than the larger 19-inch (480 mm) black light-alloy wheels, include red "722" badging, harking back to the original 722 racer, and slightly different tail lights and headlamps.

The SLR 722 can accelerate from 0 to 100 km/h (62 mph) in 3.6 seconds, 200 km/h (120 mph) in 10.2 seconds and 300 km/h (190 mph) in 27.6 seconds, and can reach a top speed of 337 km/h (209 mph).

Roadster

A roadster version of the SLR went on sale in September 2007. It uses the same supercharged V8 AMG power plant as its coupé siblings, developing 626 PS (460 kW; 617 hp), to propel it to a top speed of 334 km/h (208 mph) and a 0 to 100 km/h (62 mph) acceleration time of 3.8 seconds.

However, as a convertible the roadster was burdened with extra weight, which affected performance and handling. The Roadster's roof is made from a "newly developed material" and does not take the form of a folding metal arrangement, as is common on many modern cars. Following a manual unlatching, it takes ten seconds to fold away electrically. According to an official Mercedes document, the cabin of the roadster is capable of allowing conversation between driver and passenger up to a speed of 200 km/h (120 mph) with the roof retracted. This roadster is aimed to compete against other sports cars such as the Pagani ZondaF Roadster.

Roadster 722 S (2009)

A limited edition (150 units) of the 722 roadster. It can reach 100 km/h (62 mph) from standstill in 3.6 seconds and has top speed of 334 km/h (208 mph). The model went on sale in January 2009.

722 GT (2007-)

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 in (483 mm) OZ racing wheels. The front grill vents are removed and larger, free 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 398 kg (880 lb) and reduced its dry weight to 1,300 kg (2,900 lb) . The engine remains in relatively stock specification but now produces 680 PS (500 kW; 670 hp) and 830 N·m (610 lb·ft) at 1.75 bar (175 kPa) boost. Inside, the car is stripped out with only the essential functions being available, controlled from a carbon fibre binnacle. New carbon fibre door panels and full roll cage complete the transformation.

Renntech announced 21 SLR McLaren 722 GT would be available to the North American market exclusively through RENNtech.

Stirling Moss (2009)

he SLR Stirling Moss is a limited edition (75 vehicles) of the series, which uses a speedster styling that does not include roof or windscreen. The design is inspired by the 300 SLR race car, and was designed by Korean designer Yoon Il-hun. It was to be the last series of the McLaren SLR built under the partnership between Mercedes-Benz and McLaren, until McLaren announced their own final edition of the SLR in late 2010.

The supercharged V8 engine is rated 650 PS (480 kW; 640 hp). The car's top speed is 350 km/h (220 mph) with acceleration from 0 to 100 km/h in less than 3.5 seconds. The car is approximately 200 kg (440 lb) lighter than the regular model.

The SLR Stirling Moss began production in June 2009, after SLR Roadster's production ended in May 2009. All 75 cars were produced by December 2009. The SLR Stirling Moss was available only to SLR owners.

The vehicle was unveiled at the 2009 NAIAS.

McLaren Edition (2011)

n December 2010, more than a year after the SLR was discontinued, McLaren announced a final body conversion of the supercar. The 25-unit limited McLaren Edition is based on any earlier variant of the SLR besides the Stirling Moss and includes revised bodywork (front and rear bumper, grille, top shell, side gills, rear diffuser, rims) and interior parts, along with upgraded steering and suspension components and a new sports exhaust.