Houston, it appears we may have a problem. 167.31 which addresses vehicle transport applies the definiton of 340.01(74). The concealed carry statute 174.60 applies the definition to "motor" vehicles only.
340.01(35)
(35) "Motor vehicle" means a vehicle, including a combination of 2 or more vehicles or an articulated vehicle, which is self-propelled, except a vehicle operated exclusively on a rail. "Motor vehicle" includes, without limitation, a commercial motor vehicle or a vehicle which is propelled by electric power obtained from overhead trolley wires but not operated on rails. A snowmobile and an all-terrain vehicle shall only be considered motor vehicles for purposes made specifically applicable by statute.
As I interpret 340.01(35) loaded handgun carry will only be allowed in vehicles that meet the definition of a "motor" vehicle and ATV's. ATV's are specifically applicable in 175.60 so are considered motor vehicles for the purpose of handgun carry. However, what about snowmobiles and UTV's. It would also appear that carry of a loaded and uncased handgun would not be lawful on a bicycle, horse drawn vehicles, hay wagons, pull behind trailers or any other vehicle that is not motorized.