Should we convert vehicles to run on natural gas? Here's an article on the subject. Cars will run on natural gas, just fine. But there are some significant problems with conversion, much of which is not actually technical but is political.
Of course, natural gas is abundant, and is therefore cheaper than gasoline, right? On the other hand, gasoline would be a lot cheaper but for government perversion of the market, and how much do you want to bet that if natural gas were the automotive fuel of choice, government would screw that up, too.
Because it isn't actually about fuel. It's about who is the boss of you.