As of this writing, the car is about 2.1 million miles away from Earth and hurtling toward Mars at about 43,145MPH (6,755MPH away from Earth). It won't actually orbit Mars or venture into the Asteroid Belt, as Musk suggested -- if it keeps on its current trajectory, it should venture just past Mars before being pulled back toward the center of the system. You can find out when the car will get relatively close to Earth or Mars.

Don't expect the car to get close to other celestial bodies very often. Its closest approach to Mars in the near future will be on October 7th, 2020, when it drifts within 0.05AU* of the planet. And Earth? Pearson told The Verge that one of the car's closest approaches to home won't occur until 2091. It'll actually drift far from Earth at more than 2.3AU away. Until someone can justify sending a spacecraft to pick up the Roadster, sites like Pearson's may be your only real way of knowing what Musk's former ride is doing.

*Astronomical unit (AU, or au), a unit of length effectively equal to the average, or mean, distance between Earth and the Sun, defined as 149,597,870.7 km (92,955,807.3 miles) - Encyclopedia Britannica.