Petrol Smell

1954 Mercedes 300SL Gullwing. If you are a bit of a car fan you must be visualizing this car in your mind right now. Well, the SLS wants to be the reincarnation of the famous Gullwing. That’s why it keeps almost the same proportions as the old Gullwing and it has the gullwing opening doors.

The SLS AMG is a two-seater supercar which main competitors are the Porsche 911 Turbo and Audi R8 V10. However, the SLS in front mid-engined and rear-wheel-drive.  Laps Nürburgring in 7 minutes and 40 seconds, which is quite a fast time.

AMG developed the whole SLS from scratch in a 37 month development programme. The only parts carried over from other AMGs are the front brake disc (from SL65) and the optional ceramic brake setup (from the E63).

Mercedes designed the all-aluminium chassis. The spaceframe is fabricated almost entirely by hand and weights 241kg. It is composed by 146 extruded sections, 16 castings, and 197 sheet aluminium parts. All this parts are joined by bonding, riveting, bolting and welding.  4% of the chassis is made out of steel.  The SLS’s chassis dynamics were fully developed using simulation. Then they took three different prototype set-ups to the Nürburgring for testing. AMG rejected making the chassis of carbon-fibre because this would have meant making a collectors car. What they wanted is to see the car in the roads.

In terms of suspension AMG wanted to make a very pure sports vehicle so they decided to go for a passive suspension. However, all its competitors have active suspension. So we may see an active suspension version coming soon… Lots of effort was put to reduce the vehicle’s unsprung mass.

A naturally aspirated V8 mounted behind the front axle powers the SLS. It is based on the engine used in the E63 sedan. The capacity of the engine is of 6,308cc. The main changes made to the heart of the car are a new exhaust system and going to a dry sump. The engine weights 205kg. New forged pistons reduce the weight in 62.5g, the crankcase is 4kg lighter, the usage of aluminium bolts saves 600g also. The intake manifold is made of magnesium. Aids like brake energy regeneration help reduce the fuel consumption.  The dry sump uses a 5 litre tank with conjunction of a 700litres/minute pump, the system is filled with 13.5litres of oil which is refrigerated by two heat exchangers in the front wheel arches, each one with a blower fan.

The engine is linked with the transaxle through a 1.64m, 25kg of weight, sand cast aluminium torque tube which, at the same time, helps transfer crash energy away from the cabin. Inside the torque tube a carbon-fibre driveshaft (only weights 4.7kg) transmits the power to the transaxle. The transaxle comprises a Getrag seven speed dual-clutch transmission (DCT) and a limited slip differential.

The SLS comes equipped in either Michelin Pilot Sport 3 or Continental Sport Contact 5P tires. Runflat tires were rejected on comfort grounds. The aluminium wheels are supplied by Alcoa, the 19-inch front wheels weight 9.6kg, the 20-inch rear wheels weight 10.2kg. They house cast-iron Brembo brakes as standard. They can be upgraded to ceramics (402mm x 39mm front, 360mm x 32mm rear) made by SGL Carbon.

The SLS can generate up to 1.2g lateral acceleration (one of the reasons to adopting a dry sump). Hand-build engine. Front mid-engined, gear box at the rear. Weight distribution 47:53

More than 40 prototype vehicles have been on test around the world since summer 2008. In total these cars have clocked more than 1.25 million kilometres both on proving grounds and an public roads. AMG is currently developing an electric version

More information can be found in the following chart.

References:

http://www.mercedes-amg.com/

http://www.sls-amg-special.com/com/en

Vehicle Dynamics International magazine. January 2010.

Automotive Engineer magazine. November/December 2009.