The all-electric Nissan Leaf is now officially on sale, advertised as the first mass-market battery-operated car on the market. It uses no gasoline — and has no tailpipe emissions, because it has no tailpipe.And even though it's battery powered, like a golf cart, it's a real car, fun to drive, with comfortable seating for up to five people and styling that's mainstream, not quirky like some of the hybrids and earlier electric cars.For many, this even will be a practical car, one that can meet their everyday transportation needs — especially if they live, work and shop within a small...