Gasoline powered cars/trucks are quickly converted to propane with significant fuel savings. Diesel engines cannot be converted to run on propane only but propane injection is apparently possible. The links below are found by simply searching the internet. It might be promising for owners of diesel cars/trucks/SUV's etc.

Diesel propane injection systems, computer programmers, water vapor air fuel system seperators
Nexgas, LLC - Diesel Propane Injection Kits, Propane Conversion Kits, Natural Gas Conversion Kits
Check out our selection of Nitrous Injection Kits, Propane Injection Kits & Fuel Additives by top names like Bully Dog and Gold Eagle. - SuperTruck Essentials

Perhaps stationary diesel engines (generators, water pumps etc) could benefit from this techology. Lately, diesel fuel for generators skyrocketed as most of us noticed...

Bear in mind, I don't import of sell any of the units above. Please don't email me for more info... I just found this today (internet).