See How Teslas Are Basically Boats Futurism calculated this rocket-boosted Roadster would produce 2.5 Gs of force on the driver, so the roller coaster analogy tracks. But so do the risks. Rocket-powered cars are common for professionals attempting to break land speed records, sometimes reaching over 700 mph. But those cars aren't street legal; manufacturers usually throttle luxury sports cars at an arbitrary speed in the interest of safety. It's similar to the difference between NASCAR's "stock cars" and the fully custom-built chassis and engines of IndyCars or F1. Existing automotive regulations don't account for rocket boosters. That means any hypothetical Roadster 2.0 (it's already been 4 years since the car was announced) must go through an entirely new approvals process that doesn't yet exist. What does it look like to regulate a brand-new kind of vehicle? Musk is selling his SpaceX rocket package as if it were another trim level, rather than a complete reimagining of what a street-legal vehicle can be. But he might believe he's found a shortcut. In 2018, Musk first detailed what he thinks this rocket thruster option plan will look like: