function setSelectedCar() {
	var selectedcar = param_getParam(param_parseURL(), "vehicle_choice");
	var vehicleselect = document.getElementById("vehicle_choice");
	
	for(var i=0; i < vehicleselect.options.length; i++) {
		if(vehicleselect.options[i].value == selectedcar) {
			vehicleselect.selectedIndex = vehicleselect.options[i].index;
		}
	}
}

setSelectedCar();