Make your car with a conventional engine, but make it switchable between gasoline and CNG. For short runs around town, CNG is cheap and clean-burning; use it for that. For distance travel, gasoline has the energy density you can’t do without - use it for that.And just pretend that the CNG gets converted to electricity first. Or else actually use a generator to convert the power to electricity and dedicate an electric motor to each wheel. Instant electric car!!
I like the CNG idea. Some delivery companies have converted to CNG with their local delivery vans and smaller trucks. I talked to a driver awhile back about their switchover and he said it’s worked out well for them.
Honda Civic natural Gas
http://automobiles.honda.com/civic-natural-gas/