While 203 mph is quite fast its worth noting that dodge quotes a 199 mph top speed for the regular challenger srt hellcat so 137 horsepower nets a gain of 4 mph this 203 mph run is still. Speculating on the top speed of a car like the demon is actually a pretty complicated proposition but if youre looking for a quick and easy answer here it is 168 mph. Want to know what the top speed of the 2018 dodge challenger srtr demon is we got behind the wheel of our dodge demon for a top speed run see how well it performed in its stock form and hear the supercharged 62l hemir srt demon v8 engine in action