We don't actually know that. Maybe he broke some future law against time travel, came back and could not refuel so got stuck here. The whole space thing could be cover to find whatever type of fuel he needs. Hum, sounds like a good movie plot.
Were do you live? Have they started charging you guys a special lic fee to make up for you not paying your share of road construction cost. Gas tax is usually big part of that. I have nothing against them. The more people who drive them the lower gas price gets for rest of us. Thanks.