The Mercedes-Benz S Type – also known as the 680 S because of its 6.8-litre engine capacity – was launched in 1927 as an evolution of the Mercedes-Benz Model K super sports car. It established the legendary family of heavyweight supercharged cars that included the SS and SSK models from 1928. The cars dominated racing history over the years, but could also be bought as conventional road vehicles. All vehicles in this family had a six-cylinder in-line engine with a supercharger to increase output. Power was also boosted by the dual ignition. Each cylinder had two spark plugs, one fired by a battery ignition and the other by a high-voltage magneto ignition.