Bruce Jenner -- Wrecks Truck in Brutal Off-Road Race

Bruce Jenner got tossed into a Mexican ditch, and is lucky to be alive ... after wrecking his million dollar ride in the legendary Baja 1000 off-road race.

Bruce and his son Burt Jenner were taking part in the brutal competition -- in which multiple drivers and spectators have been killed -- when their suped up truck rolled on Thursday.

We're told Bruce was behind the wheel around mile 170 ... when he veered into the ditch and ripped off the power steering line. He and Burt had to wait a few hours for their crew to make it to their location.

As we previously reported ... sponsors and investors sunk a million bucks into the truck so Bruce and Burt could race.

During the break, the Jenners drank beer and ate pizza with some locals. When the crew showed up the team leader said they'd have to pull out of the race because -- keeping it real -- they lost too many hours after the wreck. They had no chance of winning.

At least Bruce still has his gold medal.