L V6 SL 300: (2009–2011), 3.0 L V6 SL 350 (3.7): (2003–2006), 3.7 L V6 SL 350 (3.5): (2006–2011), 3.5 L V6 SL 500 (5.0): (2001–2006), 5.0 L V8 SL 500 (5.5): (2006–2011), 5.5 L V8, marketed as SL 550 exclusively in North America SL 55 AMG: (2002–2008), 5.4 L V8 SL 600: (2002–2011), 6.0 L V12 SL 63 AMG: (2008–2011), 6.2 L V8 SL 65 AMG: (2004–2011), 6.0 L V12 SL 65 AMG Black Series: (2008–2011), 6.0 L V12 R231 (2012–2020) Mercedes-Benz launched sixth generation SL, internally designated R231, at the North American International Auto Show in January 2012. The R231 introduced aluminum bodywork, its weight advantage offset by higher safety and convenience equipment. New features included a system markete4d as 'FrontBass', which used space in the aluminium structure ahead of the front footwells as resonance spaces for the bass loudspeakers. Additionally, standard equipment included an adaptive windscreen wipe/wash system which supplied fluid from the wiper blade itself, as needed and depending on the direction of wipe. The R231 was available with two suspension systems: semi-active adjustable damping as standard and active suspension system ABC (Active Body Control) as an extra-cost option. Both types featured electro-mechanical, speed-sensitive power steering, which allowed the variable steering ratio across the steering wheel angle. The R231 was longer and wider than its predecessor. Shoulder room is increased by and elbow room . A mid-cycle update was introduced in 2016 for the 2017 model year along with revised engine and transmission options. A 9G-TRONIC Plus 9-speed automatic transmission was fitted to the SL-Class for the first time (SL 400/SL 450 and SL 500) while AMG SPEEDSHIFT MCT and AMG SPEEDSHIFT Plus 7G-TRONIC 7-speed automatic transmissions for SL 63 AMG and SL 65 AMG respectively remained unchanged. SL 350 was renamed as SL 400 (SL 450 for the North American market). R231 had a revised front end, front grille treatment, and larger non-functional side 'vents' behind the front wheels. It also received adaptive LED front headlights with integrated daytime running lights and turn signals, leaving the below-bumper intake area free from lighting. The LED tail lights received single-colour red lenses (for North American market) or red-and-amber lenses (for the European and international markets) instead of the red and white lenses of the pre-facelift models. A slight revision to the folding 'Vario-roof' hardtop meant it could deploy at up to without the luggage compartment partition having