The Perth-born Star Wars actor - more noted for his long distance motorbiking exploits - got stuck "in the middle of nowhere" in his old MG sports car.
He ran out of fuel in Utah and told followers on twitter he was saved by a woman biker called Madeleine Velazquez - even posting a picture of her on the social network site.
"This kind lady Madeleine helped me when I had run out of petrol yesterday in Utah. She gave me spare bottles that got me going to the next petrol station," said McGregor.
"Followed me to make sure I made it and when I didn't she rode ahead and came bCk (sic) with enough to get me there. She's a true adventure biker and her website is called Missrider.com She was my guardian angel yesterday when I was stuck in the middle of nowhere!"
Meanwhile New York actress Jennifer Connelly has joined McGregor in the upcoming adaptation of American Pastoral.
The Noah actress will star opposite McGregor in the movie version of Philip Roth's Pulitzer Prize-winning novel. Phillip Noyce is on board to direct Lakeshore Entertainment's third Roth adaptation.