snowmobile, vehicle designed to travel over snow, ice, and similar surfaces that offer limited traction and weight-supporting capability. As the performance of the vehicle depends to a large extent on keeping its weight as low as possible, there is no enclosure for the driver and passenger, who ride exposed, as on a motorcycle. Since the two-cycle internal-combustion engine and the Wankel engine are lighter for a given horsepower than a four-cycle engine, they are preferred for powering snowmobiles. The vehicle is supported and moved by one or two endless treads, similar to those used on military tanks and construction vehicles, except that they are of the lightest practicable weight. The driver steers by manipulating handlebars that control skilike runners on the front of the vehicle and by shifting his body weight.