Saw a new F150 that had been converted to natural gas/gasoline. It had a 25 gallon tank mounted in the bed of the truck and was covered by a rubber mat. The truck gets 16 mpg in either mode but the natural gas is $1.00 per gallon if you can find it. Some of the truck stops have natural gas for the large trucks but the connectors will not fit the ones in the p/u. The truck was purchased in Oklahoma. They will give you a rebate of $9000 to cover the cost of the conversion. The driver said that one other state gives the rebate but he couldn't remember which one. I like the idea of the conversion but it might be awhile before it is practical on a large scale.
I am reading a book about anti-gravity. It is really hard to put down.