I worked for a sand and gravel company in California in the 1970's that ran all its "gasoline" vehicles on LP gas. If it was not Diesel powered, it ran LP. The conversion is fairly straightforward- - - -install a high pressure fuel tank, run liquid LP to an evaporator chamber that turns the liquid into a gas with hot coolant, and pipe the vapor to a throttle body or a gasoline carburetor with a cutoff valve in the gasoline line, if you want dual-fuel capability. Since the LP displaces a certain volume of air as it passes through the throttle valve, the engine loses at least 10% of its power when running LP, compared to gasoline. "Propane" is actually a misnomer, as most LP gas is a Propane/Butane mixture with a variable percentage depending on the weather. Butane produces more BTU's than Propane, but it "freezes" (becomes liquid) at 32 degrees F. "Winter" mix LP contains a higher percentage of the more volatile Propane, which evaporates at -70 degrees F. or so, but doesn't have the energy output of Butane.
I've never seen a "factory" LP gas system on a car or truck- - - -we did all the vehicle conversions with aftermarket adapter kits. Some farm equipment and a lot of forklifts and other industrial equipment are set up for LP from the factory. The company I worked for also had its own LP gas refueling pump, and a 1,000 gallon LP storage tank.
Jerry
