There are many reasons to like Tesla Motors’ new aerodynamic sedan without a tailpipe, in production for the last year. Consumer Reports called it the best car they have ever tested, electric or not. “Filling up” my Model S overnight after driving 250 miles costs less than $10 of electricity, whereas my trade-in required $60 of gasoline.

Most electric vehicles are mere modifications of an existing car model; take out some machinery under the hood, fit in some new. But the Model S shows what a fresh start can do. The floor is the rigid compartment housing 7,000 small batteries. The quiet electric motor is between the rear wheels; there is no transmission. Together this makes for a low center of gravity and excellent stability.

The crash tests reported last week turned out, as Tesla’s designers had predicted, to be five star as well. Indeed, another best ever. What’s under the hood is a well-designed crumple zone, with no heavy machinery to threaten front seat occupants. It’s used as the second trunk. To see any machinery, one must crawl under the car.

The Tesla itself may have zero emissions but the electrical energy has to come from somewhere. Here in Seattle, 98 percent of our electricity comes from sun-powered renewables: hydroelectric, photoelectric, and wind. Switzerland also has 98 percent clean electricity, half from hydro and half from nuclear, also clean except for the mining of uranium. But most places get their electricity from some less guilt-free mix of clean and traditional. If I recharge while driving through Wyoming, the electricity will come from burning the most damaging fossil fuel of all,