Dozens of propane-powered vehicles are converging on Des Moines early this morning as part of a demonstration of fuel versatility. Ward Lenz, a fuels analyst for the Iowa Department of Natural Resources, says the “Propane Road Rally” is headed through Iowa.The dozens of regular-looking but propane-powered vehicles are being driven to the Propane Vehicle Conference and Expo in Kansas City, Missouri, which is now underway and runs through tomorrow.Most of the converted cars, trucks and vans have 40-gallon propane tanks underneath instead of gasoline tanks. The fuel is the same stuff many Iowans use in their backyard grills. Lenz says propane and gasoline are usually comparable in price, but he says propane has one big plus, as it burns cleaner and puts out less emissions into the air.He says some of the drivers of these vehicles will travel 46-hundred miles, from as far away as Canada and Mexico, to attend the conference. The Road Rally is stopping at the “Flying J” truck stop in Clive at 6:30 this morning, before headed south to Kansas City.