He mentions the possibility of making the fuel from solar power, water and CO2 on Earth in the same way he plans to for Mars. It wouldn't make economic sense no

He mentions the possibility of making the fuel from solar power, water and CO2 on Earth in the same way he plans to for Mars. It wouldn't make economic sense now though. If you care about the environment that much, use the same process to make the same methane and run your ICE car off it. That's old tech.