The Mercedes-Benz SLR McLaren (C199 / R199 / Z199) is a grand tourer jointly developed by German automotive manufacturer Mercedes-Benz and British automotive manufacturer McLaren Automotive and sold from 2003 to 2010. When the car was developed, Mercedes-Benz owned 40 percent of the McLaren Group and the car was produced in conjunction between the two companies. The "SLR" name is an abbreviation for "Sport Leicht Rennsport" (Sport Light Racing), and was an homage to the Mercedes-Benz 300 SLR which served as the car's inspiration. The car was offered in coupé, roadster and speedster bodystyles, with the latter being a limited-edition model.
History
At the 1999 North American International Auto Show, Mercedes-Benz presented their Vision SLR concept, inspired both by the Mercedes-Benz 300 SLR Uhlenhaut Coupé of 1955, which was a modified Mercedes-Benz W196S race car, and the design of closed-wheel Formula One cars, a field in which they had prior experience from Mercedes-Benz competing in Formula One in the past as constructor also winning back to back championships in their debut season 1954 then 1955. Also during the jointly developed project of Mercedes-Benz SLR McLaren in 2003 Mercedes-Benz acquiring 40 per cent ownership of McLaren Group competed in Formula One as partnership with the McLaren Formula One Team, and were developing powertrains and electronics for McLaren's Formula One cars. The car was presented as "Tomorrow Silver Arrow" in a clear reference to the Silver Arrows of the golden age of Mercedes in competition during the fifties. Later that year, during the Frankfurt Motor Show, a roadster version of the SLR concept was presented. The concept car was fitted with a 5.0-litre supercharged AMG V8 engine able to generate a power output of and of torque at 4,000 rpm, mated to a 5-speed automatic gearbox with Touchshift control.
Wanting to bring the concept to production following its positive reception, Mercedes joined forces with their Formula One partner, McLaren, thus creating the Mercedes-Benz SLR McLaren. Mercedes did the styling on the car while McLaren was fully responsible for everything else, from the design and the engineering to the manufacture and the testing of each car at the production line. During development, a pair of TVR Cerberas were modified for use as test mules for the SLR's engine. The production version of the car was unveiled to the general public on 17 November 2003 having some major design adjustments in respect of the initial design. In order to give the car the performance that Mercedes wanted, McLaren had to radically alter the concept for better weight distribution, including moving the engine almost a meter back and lowering the fuel tank. Smaller adjustments included more complex vents on both sides of the car, a redesigned front with the three pointed star plunged in the nose and red tinted rear lights.
The Mercedes-Benz SLR McLaren saw a production run of over six years. On 4 April 2008, Mercedes announced it would discontinue the SLR. The last of the coupés rolled off the production line at the end of 2010 and the roadster version was dropped in early 2009. Due to the automatic gear box, front mid-engine arrangement, and its driving characteristics, some automotive journalists classify the SLR McLaren as a grand tourer.
Technical highlights Brakes
The SLR features Sensotronic Brake Control, a type of brake-by-wire system. The brake discs are carbon-ceramic units 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 . The front discs are internally vented and measure in diameter; eight-piston callipers are used. Rear discs are in diameter with four-piston callipers. During wet conditions the callipers automatically skim the surface of the discs to keep them dry.
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 edition) for increased rear downforce, at the cost of increased steady state drag. The car has a flat underbody and a rear diffuser for improved downforce. Due to this, there was no other place for the exhaust pipes to exit, other than the sides of the car, making it another unique feature of the SLR.
Engine
The SLR has a hand-built supercharged all-aluminium alloy, SOHC 3 valves per cylinder 90° V8 engine, with a bore and stroke of and with a compression ratio of 8.8:1. The engine is lubricated via a dry sump system. The Lysholm-type twin-screw supercharger rotates at a maximum of 23,000 rpm and produces of boost. The compressed air is then cooled via two intercoolers. The engine generates a maximum power output of at 6,500 rpm and maximum torque of between 3,250 and 5,000 rpm.
McLaren took the original concept car designed by Mercedes and moved the engine behind the front bumper, around behind the front axle. They also optimised the design of the centre firewall.
Transmission
The SLR uses the AMG SPEEDSHIFT R five-speed automatic transmission with three manual modes. For durability, Mercedes selected a five-speed transmission rather than their seven-speed transmission which was more complex and used more parts.
Performance The car uses carbon-fibre reinforced plastic (CFRP) construction in an attempt to keep the weight low. Despite CFRP materials, the total curb weight is . The SLR could attain a top speed of .
Car and Driver achieved a 0 to acceleration time of 3.4 seconds, and a time of 11.2 seconds at . Car and Driver also achieved top gear acceleration and 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 magazine suggested that the times may be even lower if temperatures were lower. Motor Trend tested the SLR and achieved a 0- acceleration time of 3.3 seconds in April 2006.
Road And Track tested the car in their July 2005 Road Test and reached from a standstill in 3.5 seconds. The 0 to sprint was achieved in 7.5 seconds and a run was completed in 11.5 seconds at .
Variants
722 Edition
A new version of the SLR 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 a modified version of the engine used in the SLR generating a power output of at 6,500 rpm and at 4,000 rpm. 19-inch light-alloy wheels were used to reduce unsprung mass, while modifications were also made to the suspension, with a stiffer damper setup and lower ride height introduced for improved handling. Larger diameter front brakes and a revised front air dam and rear diffuser were fitted.
Other exterior changes include red "722" badging, harking back to the original 722 racer, black tinted tail lights and headlamps. The interior has carbon fibre trim and black leather upholstery, combined with Alcantara.
The SLR 722 can accelerate from 0 to in 3.6 seconds, 0 to in 10.2 seconds and in 27.6 seconds, and can attain a top speed of , faster than the standard Mercedes-Benz SLR McLaren. Production of the 722 Edition was limited to 150 units.
Roadster
A roadster version of the SLR went on sale in September 2007. It uses the same engine as its coupé sibling, generating a power output of , to propel it to a top speed of and a 0 to acceleration time of 3.6 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 with the roof retracted. The SLR Roadster was aimed to compete against other luxurious sports cars such as the Pagani Zonda F Roadster.
Roadster 722 S (2009)
The Roadster variant of the 722 Edition was unveiled at the 2007 Frankfurt Motor Show. The roadster has the same engine and suspension setup as the coupé along with the folding roof mechanism shared with the standard SLR roadster. It can accelerate to from standstill in 3.1 seconds and has top speed of . The model went on sale in January 2009 and production was limited to 150 units.
722 GT (2007)
The 722 GT is a racing version of the SLR 722 which was developed for a one-make racing series called SLR Trophy. The cars were built by Ray Mallock Ltd. following requests from enthusiasts with approval from Mercedes-Benz. The car has new wider bodywork to accommodate OZ racing wheels. The front grille 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 fixed racing wing and diffuser.
Under the body, the car has shed of weight and reduced its dry weight to . The engine remains in relatively stock specification but now generates a power output of and of torque at 1.75 bar (175 kPa) of boost and is equipped with a new racing filter and exhaust system. The car has a modified Eibach racing suspension with a modified stabiliser at the front that improves handling. An adjustable wheel camber along with shock absorbers with variable compression and rebound settings allows the suspension setup to be configured for different race tracks. New 18-inch OZ racing wheels with central locking nuts allow for faster tyre changes while a pneumatic jack system aids further in the process. The stock carbon ceramic braking system has been replaced with an FIA approved racing brake system with steel brake discs having a modified cooling system and balance that ensure improved stopping power. The transmission from the standard car is retained but is now configured for race use.
Inside, the car is stripped out with only the essential functions being available, controlled from a carbon fibre binnacle. The stock steering wheel has been replaced with a racing steering wheel with paddle shifters and a gear change indicator, the heated leather seats have also been removed in favour of Recaro racing bucket seats with six-point racing harness and the gauges have been replaced with a digital racing display. New carbon fibre door panels, plexiglass windows and a full roll cage complete the transformation. Although 21 was planned to satisfy the FIA’s homologation requirements, 12 was produced.
The 722 GT could accelerate from in 3.3 seconds and could attain a top speed of , which is less than the standard SLR due to added aerodynamic drag.
The SLR McLaren 722 GT was available to the North American market exclusively through their dealerships by Renntech.
Crown Edition (2008) The SLR "Crown Edition" was commissioned by the King of Bahrain as gifts for fellow Arab royals. This run of 10 cars was upgraded with 722-specification parts, including the uprated and modified engine, carbon fibre aerodynamic parts, stiffer dampers and 19-inch lightweight alloy wheels.
Stirling Moss (2009)