You can't make gasoline from switchgrass. You can make ethanol with it. Modern gasoline combustion engines can't run on pure ethanol, not without some serious modifications anyway. Switchgrass isn't a panacea but it's a helluva lot smarter than the current model using corn.

As for the running on corn oil, I think you may be thinking of the original diesel engine which was actually run on coal oil and can now run on vegetable oil. I have 2 Mercedes Benz diesels that have been modified to run on used vegetable oil. Works like a charm. And of course there's also bio-diesel which is simply refined vegetable oil, another great alternative to both gasoline as well as petroleum diesel.

John E