Mercedes-Benz will use the forthcoming Black Series SL, scooped on autocar.co.uk last week, as the basis for its new SLC supercar (pictured here in an Autocar image).The gullwing-doored SLC, which will use components from the SL65 Black Series, will replace the £300,000 SLR when the car-making arms of McLaren and Mercedes part company next year. The SLC will be developed by AMG.The SLC will use the Black Series car’s axles, which explains why the hottest SL’s tracks are so wide (70mm more at the front and 115mm more at the rear) compared with a standard SL65’s. Unlike the SL Black Series, the SLC will use a welded aluminium spaceframe, which will increase the car’s strength but reduce weight. The spaceframe will be clothed in a body made from aluminium and carbonfibre as Mercedes moves into building alloy cars for the first time.A new version of the SL65 Black’s twin-turbo 6.2-litre V8 with well over 600bhp will power the SLC; the V12 is too heavy and thirsty. New turbos have allowed AMG to add direct injection to improve economy.The transmission is likely to be AMG’s new seven-speed MCT ’box, just launched in the SL63. And there’s the possibility of a BMW M-style electronic differential; AMG is working on such a system.The SLC will feature a version of the SL Black’s pop-up spoiler, which sits flush with the rear body but rises when the car exceeds 60mph. Expect the car to use 19-inch wheels at the front and 20-inchers at the back.Mercedes will farm out the assembly of the SLC to HWA, the motorsport arm of AMG. HWA started work last year on expanding its factory in Affalterbach, stating that it wanted to “push our activities in the field of road-going sports cars”. It already builds the wide-arched CLK DTM road car and makes a replica of the original 300 SL with modern mechanicals.