Mercedes-Benz SLR McLaren (2000's)

The Mercedes-Benz SLR McLaren is an Anglo-German grand tourer car jointly developed by Mercedes-Benz and McLaren Automotive, built in Portsmouth and the McLaren Technology Centre in Woking, Surrey, England and sold from 2003 to 2009. When it was developed, Mercedes-Benz owned 40 percent of the McLaren 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.The car's base price, GB£295,337 (approx. US$450,000, €350,000, CHF 500,000 or C$ 500,000. 2009), made it the ninth most expensive street-legal car in the year 2008.

History

The 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 Nov 2003. On 4 April 2008, Mercedes announced 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 2009.

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) in diameter. 8 piston calipers are used. Rear discs are 360 mm (14 in) in diameter with 4 piston calipers. During wet conditions the calipers 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. The additional rear downforce in addition to the markedly increased aerodynamic drag increases peak deceleration ~90%.

The brakes have been strongly criticized by such review sources as Top Gear due to lacking modulation and having an on-off operation. This is due to road cars not regularly reaching normal operating temperature for ceramic discs in stop-go traffic conditions.

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 speeds above 95 km/h (59 mph) 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, 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 millimetre (3.82 in) and 92 millimeters (3.62 in), respectively. The Lysholm-type twin-screw supercharger rotates at 23000 revolutions per minute 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)@6500rpm and maximum torque of 780 N·m (580 lb·ft)@3250-5000rpm.

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 (39.4 in) behind the front bumper, and around 50 centimetres (19.7 in) behind the front axle. They also optimized the design of the center firewall.

Transmission

The SLR uses AMG SPEEDSHIFT R 5-speed automatic transmission with 3 manual modes. For durability Mercedes selected a 5-speed transmission rather than their 7-speed gearbox which was more complex and used more parts.

Performance

The car uses carbon fibre for its entire body 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 0-60 mph (100 km/h) time of 3.4 seconds, and a quarter-mile time of 11.2 seconds at 130 mph (209 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 Driverachieved 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.

Road and Track tested the car in their July 2005 Road Test and reached 60 mph (97 km/h) from a standstill in 3.5 seconds. The 0 - 100 mph (160 km/h) sprint was achieved in 7.5 seconds and a quarter mile run was completed in 11.5 seconds at 126 mph (203 km/h).

In June 2004 the SLR was tested at Nardo and performed the 0-100 km/h (62 mph) exercise in 3.2 seconds, 0-200 km/h (124 mph) in 9.6 seconds and 0-300 km/h (190 mph) in 24.8 seconds. Their 400 m (0.25 mi) time of 11.0 seconds at 133 mph (214 km/h) and 1 km (0.62 mi) time of 19.2 seconds at 282 km/h (175 mph) respectively. They also broke its claimed top speed of 334 km/h by reaching 339 km/h (211 mph).

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 (1:19.8 vs. 1:20.9). 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 miles per hour.

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)@6500rpm and 820 N·m (600 lb·ft)@4000rpm, 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 for £350,000 ($534 485 U.S.). 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 enable 0-100 km/h (62 mph) acceleration time of 3.2 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 a mere 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 Zonda F 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 on 2009-01-01 for around $750,000.00.

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 fiber binnacle. New carbon fiber 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, for €795,000 (1.2 million USD).

Stirling Moss (2009)

The 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 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 0–100 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 has MSRP of €750,000 and was available only to SLR owners.

The vehicle was unveiled in 2009 NAIAS.

McLaren Edition (2011)

In 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.

Aftermarket variants

So far, the SLR McLaren has been tuned by many specialist companies, including Mansory, Hamann, FAB Design, ASMA Design, Renntech and Brabus. Tuning car company Mansory named their model (which was based on the SLR McLaren) "Renovatio"; changes include the increase in horsepower to 690 PS from 626 PS, and cosmetic changes to the exterior and interior. Hamann named their model "Volcano"; modifications include horsepower increase to 700 PS and cosmetic changes to exterior and interior. FAB Design has turned the SLR into an even faster model, now with a 750 PS, 1080 Nm engine and a complex body kit, named "Desire". ASMA Design decided to call their car "Perfectus" and its engine now produces 700 PS and 885 Nm. Several modifications have been made to the body of the car which is dressed with naked carbon fiber and a re-styled body kit. Renntech made changes to the engine of the 722 version which, after extensive reworking, produces 740 PS. Brabus increased the horsepower of the car from 626 to 650, and made changes in the exterior and interior of the SLR McLaren.

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BMW E23 (1970's-1980's)

The BMW E23 is the first BMW 7 Series luxury car, produced by the German automaker BMW. Replacing the BMW E3 large sedan, the E23 was produced for ten years from 1977 to 1987 and was replaced by the BMW E32 7 Series in 1986.

Design and features

All E23 7 Series models (with the exception of the 745i) were built with the 12-valve M30 six-cylinder engine as used in the older E3 and E9 cars. Although most E23 engines were fuel-injected, two models (the 728 and 730) were available with a Solex four-barrel carburetor until 1979, when they were replaced by the fuel-injected 728i. Early fuel-injected models used the Bosch L-jetronic system while later models used the more advanced digital Bosch Motronic system.

The E23 7 series cars were very upscale and sophisticated for their time. They were the first BMWs fitted with service interval indicators, a 'check control' that alerted the driver to various system faults, and complex climate control systems. On-board computers and anti-lock braking system (ABS) were optional on early models but later became standard features. Also, later models (1985–1986) offered an optional driver's air bag. A variety of options included leather upholstery, several types of wood trim, power seats, seat heaters, and power windows and mirrors. Four-speed and five-speed manual gearboxes were available (depending on the year) and an automatic transmission was also available.

A minor styling update in 1983 affected the 'nose' of the car (the front 'kidney' grilles, valance/spoiler, bumpers etc.) as well as the dashboard and instrument panels which received updates plus (in the UK) the 735i received the Motronic 3430 cc engine (replacing the 3453 cc) and rear suspension modifications as well as numerous other minor changes. In the US, 1984 saw the arrival of the optional 4 speed automatic transmission (replacing the 3 speed unit previously offered), upgraded wood trim above the glove compartment and on the ashtray (previously plastic in all US models), electrically adjustable power seats and larger Michelin TRX radials with special TRX wheels (later standard on all 1985–1987 735i/L7 models) on the 5 speed manual models.

Notable versions

745i

The 745i was a special high-performance model offered in left-hand-drive European markets between 1979 and 1986. It was originally fitted with a specially-prepared 3.2 L type-M30 six cylinder engine and a turbocharger producing 10 psi of boost, BMW engine code M102.

In 1984 the engine grew to 3.4 L, BMW engine code M106, produced 6 psi intake pressure, and produced the same power output as the M102. These cars were all built with automatic transmissions (although there is documentation supporting how the ECU was modified at the factory to work with Getrag 5 speeds) and could be ordered with exotic options such as heated front and rear power reclining seats, auto-on aux interior gasoline fired heaters, leather covered cellular telephones, front and rear seat heaters, rear-armrest radio control, water buffalo hide upholstery, and burl wood trim. The water buffalo interior model was the Executive trim option, while the High Line trim package offered ivory leather interior trim including a leather dash board, sun visors, headliner, and other leather bits not offered on the Executive.

BMW designated this particular model as 745i instead of 732i Turbo due to the theoretical assumption that the turbocharged motors have about 1,4 times more power than naturally aspirated motors. Thus, 3,2-litre (3210cc) turbocharged motor has "power equivalent" of 4,5-litre (4494cc) motor without forced induction.

South African 745i

A 745i without turbocharger was built specifically for the South African market. The right-hand-drive version was not possible with the turbocharged motor due to the proximity of turbocharger in the right-hand side of engine bay. Instead, it was fitted with the detuned version of 286 hp (213 kW) dual-camshaft 24-valve M88/3 M1 Motorsport engine with a Bosch ML-Jetronic fuel injection system. This particular motor was also fitted to the first-generation M5 and M635CSi. A production run of 209 South African 745i was built from 1984 to 1986: 192 were built with automatic gearbox and 17 with 5-speed manual gearbox.

BMW South Africa ran one of these 745i models in Class A of the South African Modified Saloon Car Championship, the only BMW-Sanctioned motor sport application in the history of BMW 7-series cars.

North America and Japan

Only the 733i, 735i, and L7 were offered in these markets. As usual, BMW sold only upscale versions in these markets, usually including leather upholstery, cruise control, wood trim, power windows, power sunroof, and other options as standard. North American versions were fitted with larger bumpers (to comply with the U.S. National Highway Traffic Safety Administration (NHTSA) standards), smaller sealed beam headlights, and various forms of emissions equipment that were not found on European-market cars. The engines used in these markets had lower-compression pistons and thus were less powerful than European-market versions. Some features such as ABS were available in markets outside North America before they were fitted on American models. Many turbocharged 745i models made their way into America during the height of the grey market in the mid-1980s.

The L7 was a more luxurious version of the 735i for the American market only. It featured special leather upholstery with leather dashboard and door padding (rather than wood trim), a power glass Moonroof. and a variety of optional features as standard. All L7 models were built with automatic transmissions and a standard driver's air bag. The L7 was the first BMW sold in North America with a driver's side airbag.

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