Snowmobile Vehicle

Trail snowmobiles have had their fair share of improvements in the past 15 years as well (many of them borrowed from endeavors to produce winning mountain sleds). Heavy 'muscle sleds' can produce speeds in excess of 150 mph due to powerful engines (up to 1200 cc stock, and custom engines exceeding 1200 cc's), short tracks, and good traction on groomed trails. Sno-cross oriented snowmobiles often have a engine size cap of 440 or 600 cc's, but lighter machines with redesigned stances, formats, and weight control have produced extremely fast and quickly accelerating race sleds.
Environmental impact
The environmental impact of snowmobiles has been the subject of much debate. Governments have been reacting slowly to noise and air pollution, partly due to lobbying from manufacturers and users of snowmobiles. For instance, in 1999, the Canadian government adopted the Canadian Environmental Protection Act, but the set of rules governing pollution emissions for off-road vehicles was only released in January 2005. Another example of regulation, only four-stroke snowmobiles are allowed in Yellowstone National Park since a bylaw was recently passed to minimize CO2 emissions and noise. In Yellowstone, snowmobiles account for 80% of total hydrocarbons emissions and 50% of carbon monoxides emissions during the winter months. Although less than 2% and 1% overall annually respectively. In winter, snowmobiles only are allowed to ride on the unplowed roads used in the summer in the park. This impact accounts for less than 1% (.002%) of the park area.