it's not exactly 230 mpg...
It can go 40 miles on the battery, then the gas kicks in to help recharge it, giving it about 50mpg.
It's a good idea, but not worth the estimated $40k that they're gonna price it for. They should've waited to release it when it would be cheaper for them to mass-produce it to compete against the Prius and the Insight, rather than the estimated price be nearly two Insights.