I presume that energy density also has a lot to do with it, as others have said. Other ways that we've tried, including hydrogen cars, just don't offer the same

I presume that energy density also has a lot to do with it, as others have said. Other ways that we've tried, including hydrogen cars, just don't offer the same amount of energy density. Real volume constraints are also becoming an issue as we need more and more energy for devices. That coupled with improvements in safety and cost makes it worth it.