but we're not talking about energy density, were talking about power. If fuel efficiency was a concern then yes, gasoline is a more efficient fuel. But overall propane has more power than gasoline if the engine is tuned for propane fuel. Even with reduced fuel economy, propane is a MUCH cleaner fuel, it bothers me that everyone is going nuts over hydrogen. You need electricity to get hydrogen, where does the electricity come from? Nuclear Plants, Hydroelectric Plants, and worst of all Coal Plants. Propane requires none of the above, is cleaner than gasoline, and most carburated engines can be modified to run propane for less than $200. Fuel injected systems are also available. Imagine if all the carburated engines in the us ran on propane, we would be much better off due to the fact that these engines are the gas guzzlers. They are the cars getting bad mpg's and the reason we are dependent on foreign oil.