The 2018 Dodge Challenger SRT Demon made 840 horsepower from its supercharged 6.2-liter HEMI V8, ran the quarter mile in 9.65 seconds, and became so extreme that NHRA banned it from record-legal drag competition. Dodge built only 3,000 for the US market, charged extra for a passenger seat, and gave it a widebody kit just to put the power down. Read on to find out what it took to build a street-legal car too fast for its own sport’s rulebook.