You gotta be kidding.
The diesel engine was designed to run on peanut oil.
It's much easier to run alternative fuels in a diesel engine than in a spark ignition engine.
You have to add a plug to get it burn Propane. The military is working on Spark Ignited Heavy Fuel engines to meet the 2010 one fuel requirement, they were gasoline engines 1st. As far as I know running gasoline or any ethanol type fuel is a no go as well in a diesel as well.
IMHO versatility will be the key in the future, it will not be the price of the fuel, but if you can get it and burn it.
Rudolph Diesel originally used coal dust in his primitive engine - which exploded and nearly killed him. He later drowned in the English channel.
But still, the diesel offers a wider range of possibilities than a gasoline engine. Also, there is a grain crop that, per bushel to the acre planted, will outproduce soy, wheat, corn, or any other consumable by three to five times AND the oil (most varieties have a 40-45% oil content) is a volatile substance from the start, meaning less energy is required to distill it into fuel. That crop is mustard and the substance is mustard oil and when combined with diesel from crude and biodiesel from other grain sources, America could be on her way to retiring Arab's influences.
Canada - our close neighbor produces about 60% of the world's mustard seed. Most of America's agrarian climate could yield two harvests per year. We ought deal with them for the seed and enhance domestic production rather than continue bearing the OPEC's noose on our necks.
True Diesel Engines run on any thing that is Greasy.
barbra ann