At least it makes a tiny bit more sense than sending a car with an internal combustion engine to a planet with no oxygen in its atmosphere. It sends a very clear message: you're not gonna be driving that gas-guzzling SUV on Mars. Electric is the future.

The next mission might actually carry a Tesla rover to the surface. Then maybe a large battery-backed solar array so the rover doesn't need to worry about its energy budget anymore. The "silly" mission could even help Tesla/SpaceX gain important insights about how their batteries fare in space. Never underestimate Elon Musk, even when he seems to be having too much fun.