DENVER (AP) _ Bobby Unser went through a ``harrowing, life-threatening'' experience in Colorado's back country, a federal judge said Thursday before convicting the former race car driver of illegally driving his snowmobile in a federal wilderness area.

U.S. District Judge Lewis Babcock fined Unser $75.

Unser could have faced a $5,000 fine and up to six months in prison for the misdemeanor charge. But the three-time winner of the Indianapolis 500 wasn't ready to just pay the fine and go home to Albuquerque, N.M.

``It's not about money,'' said Unser, who added that he ``almost assuredly'' will appeal the conviction to the 10th U.S. Circuit Court of Appeals.

Babcock called the case unique and sympathized with the 63-year-old Unser, who wandered through the South San Juan Wilderness for two days in December after his snowmobile broke down.

But Babcock rejected the defense's argument that Unser's crisis should outweigh any possible violations of the Wilderness Act of 1964, which forbids the use of motor vehicles in wilderness areas.

The race car driver and his attorney, Armand Carian, said if Unser and a companion crossed into the wilderness area, they did so unknowingly and while struggling against a ground blizzard and plunging temperatures.

The evidence doesn't support that scenario, Babcock said.

``A reasonable person in those circumstances would have turned right around and looked at their tracks and gone out,'' he said.

Prosecutors argued, and the judge agreed, that Unser and his companion, race car driver Robert Gayton, kept pushing ahead.

Todd Welch of the Denver-based Mountain States Legal Foundation said his organization will represent Unser if he appeals.

``I'm obviously extremely disappointed,'' Unser said. ``I didn't do anything wrong.''

While saying he wouldn't ``cry over spilt milk,'' Unser added that he wouldn't let the matter drop. He has gained the support of some members of Congress who say the U.S. Forest Service is running amok.

Unser said he believes the government pushed the case because it could make a point with such a high-profile defendant. He said he doesn't oppose wilderness areas but will continue to defend himself as a matter of principle.

Federal prosecutor Robert Kennedy agreed with Unser that important principles were at stake.

``There's a lot more involved than $75,'' Kennedy said. ``There are a lot more principles involved.''

The regional chapter of The Wilderness Society echoed the sentiment. Suzanne Jones of the Denver office said she was happy to see the government go to court to protect the Wilderness Act.

``We commend the Forest Service for enforcing the laws of the land and the court for upholding them,'' she said.

Unser said he and Gayton, also of Albuquerque, had planned a short snowmobile trip Dec. 20 from Unser's ranch near Chama in northern New Mexico when blowing snow created whiteout conditions and caused them to become lost in the forest for two days.

The two dug a snow cave one night after trudging through waist-deep snow. The next day, Unser and Gayton slid down a steep, snowy cliff and walked 18 hours until they found a barn, which had a telephone.

Unser called for help, and the men were taken to the hospital. They were treated for exposure and minor injuries.

Defense attorneys claimed that Gayton was not cited because he wasn't a celebrity.

Forest Service special agent Charles Burd, who testified against Unser, said Gayton initially couldn't be found, and the case was then turned over to prosecutors.

Kennedy declined to comment on why Gayton wasn't arrested.