The Mint 400 is the oldest and most prestigious off-road race in America. Held annually in March, over 550 race teams in 80+ classes compete for two days.
151.625MHz FM is an active Mint 400 Operations channel, with the base putting out a pretty good signal around the LV area. I got pretty strong as I approached Henderson Executive Airport on St Rose Friday, so may be out in the Sloan area.
Some competitors seems to just use MURS/BRS, some have their own licenses, and some just buy radio systems from a company like Radio Radios Inc that come pre-loaded with simplex VHF or UHF channels & CTCSS/DCS, and to-hell with any interference to licensed users...