The Bowie song is apt, and not just because of the Mars reference. Musk plans to have "Space Oddity" playing on repeat in the Roadster. The car will travel at a max velocity of 7 miles per second and will travel about 250 million miles from earth – unless another rocket-building billionaire tries to one-up Musk, those are absolute velocity and distance figures that are unlikely to be challenged by any other four-wheeled vehicle, ever.
On this planet, the fastest something you could technically refer to as a car has gone is 763 miles per hour, which was Thrust SSC. Without the hinderance of either atmospheric resistance or gravity, the Roadster will travel an astonishing 25,200 miles per hour – that's what 7 miles per second works out to. And the highest mileage car? Well, it's Irv Gordon's Volvo P1800S, and it has just over 3 million miles on it. He's not going to surpass the Tesla's distance record anytime soon. (And yes - direct comparisons are kind of silly, but so is shooting an electric sportscar at Mars, isn't it?)
For its part, the Falcon Heavy rocket was designed to help carry humans into space, including both the Moon and Mars.