The Dodge Challenger Demon is the fastest model while running in high octane mode. However, in-stock mode, the title goes to the Challenger SRT Super Stock, which receives more than 807 horsepower from its 6.2-liter, 8-cylinder, supercharged engine. That is just one horsepower short of the Demon's impressive 808 hp. The impressive aspect is that the new SRT Super Stock does so without high octane fuel in the engine. Plus, it is likely possible to get even higher horsepower out of your vehicle.