TRAVERSE CITY, Mich. (AP) Ed Klim was snowmobiling recently in the northern Michigan countryside when a cross-country skier beckoned. Klim braced for a lecture about spoiling the peaceful setting.
Instead, the skier stared at Klim's idling vehicle. ''What's that?'' he demanded. ''It looks like a snowmobile, but it doesn't sound like one.''
''It IS a snowmobile,'' replied Klim, president of the International Snowmobile Manufacturers Association, based in Haslett.
To be precise, it was a prototype model with a four-stroke engine part of a new generation of sleds designed to address two of the biggest complaints about snowmobiles: noise and pollution.
Over the next couple of years, manufacturers will begin mass producing four-stroke snowmobiles, which run more quietly and generate fewer emissions than the two-stroke engines powering today's machines.
Additionally, companies say they are still trying to cut sound and emission levels in two-stroke engines, which offer more speed and better performance than the new four-stroke varieties.
''Many of our customers have told us they want machines that are quieter and cleaner,'' Klim said in an interview last week.
Pressure from government and environmentalists is another incentive.
The U.S. Environmental Protection Agency plans to issue suggested pollution rules for snowmobiles and other off-road vehicles in September.
And the National Park Service announced plans last year to prohibit snowmobiles in most of the parks. Legislation pending in Congress would overturn the ban, while the industry is suing to keep snowmobiles in Yellowstone National Park in Wyoming.
The challenges come as the sport gains popularity and becomes increasingly important to the winter economy in snow country. There are about 1.7 million registered snowmobiles nationwide, including 357,000 in Michigan, the most of any state.
The industry says it generates more than $7 billion a year through sales of machines and accessories and by bolstering winter tourism.
For manufacturers, the mission has been to produce machines that are more environmentally friendly without sacrificing the power and handling many riders crave and without pricing customers out of the market.
Arctic Cat, based in Thief River Falls, Minn., announced in December a limited production of 100 machines. The company plans full production this year, with the machines reaching showrooms by next winter.
Polaris Industries of Medina, Minn., introduced a four-stroke engine last month. It plans limited production this fall and the first dealership sales for the 2002-03 season.
The two other major manufacturers of snowmobiles for the U.S. market Bombardier Inc. of Valcourt, Quebec, and Yamaha Motor Corp. U.S. of Cypress, Calif. also are developing quieter and cleaner technology, Klim says.
The four-stroke sled is a bit heavier and slower than the two-stroke. Still, Polaris says its four-stroke will hit around 65 mph more than enough for many riders. The typical two-stroke can reach 85-95 mph, depending on surface conditions and altitude, Klim says.
''We envision the four-stroke being popular with customers who want to take their families out of doors for trail riding and touring,'' said Tom Tiller, the Polaris chief executive officer.
He said it probably would cost 15 percent to 20 percent more than a comparable two-stroke machine.
Four-stroke engines reduce emissions of hydrocarbons a leading component of snowmobile air pollution by up to 80 percent and carbon monoxide emissions by more than half, Klim says.
They do not produce the smelly blue smoke typical of two-stroke snowmobiles and are more fuel-efficient because they use electronic fuel injection, Arctic Cat says.
Rob Goepfrich, an Arctic Cat dealer in Traverse City, says he is eager to begin selling the four-stroke sled.
''We've had quite a few customers regular Joe snowmobilers who have heard about it and want to learn more,'' he said.
The industry's progress with four-stroke engines is encouraging, said Sean Smith, public lands director for the Bluewater Network, an environmentalist group in San Francisco that opposes snowmobiling in national parks.
''We haven't seen the data that shows the machines are definitely cleaner and quieter, but it's good that they are making the effort and moving in the right direction,'' Smith said Monday.
Even if the industry's claims hold up, he added, snowmobiles are bad for national parks because they harass wildlife and endanger public safety.