Right now, if you want an alternative-fuel vehicle, you have to pick from offerings that either require gasoline or an electrical outlet. The gas-electric hybrid and the battery-powered car — your Toyota Priuses, Chevy Volts, and Teslas — are staples in this space. There are drawbacks for drivers of both types.

You still have to buy gas for your hybrid and you have to plug in your Tesla — sometimes under less than favorable conditions — lest you be stranded someplace far away from a suitable plug. Beyond that, automakers have been out to find the next viable energy source. Plug-in vehicles are more or less proven to be the answer, but Toyota and a handful of other carmakers are investigating hydrogen.

That's where the Toyota Mirai comes in. It's an ambitious project for Toyota because the fueling infrastructure for this car is minimal. There are only 33 public hydrogen-filling stations in the US, according to the US Department of Energy. Twenty-six of those stations are in California, and there's one each in Connecticut, Massachusetts, and South Carolina.

If you include public and private hydrogen stations, then the total climbs to 58 — nationwide. Compare that to the more than 15,100 public electric-charging stations and the 168,000 retail gas stations in the US, and you can see the obvious drawback of hydrogen-powered cars. Despite this, the Mirai is an interesting project, if for no other reason than the fact that it's different.

We spent three days with the Mirai in San Francisco. Here's how it went: