Carpentier drove for Waltrip, the owner/driver at Michael Waltrip Racing, earlier this season for the road race at Infineon Raceway in Sonoma, Calif., and finished 11th after starting 38th.
"We had a really good run at Sonoma once we got familiar with each other," Carpentier said. "I'm happy to have the opportunity again."
Carpentier is considered a road-racing expert. He competed in Champ Car and the Indy Racing League before racing in Cup last season.
"Patrick is being rewarded for perseverance," Waltrip said. "He and I had a little deal on the side [at Sonoma]. If he was able to finish solidly and wanted to do it again, I would ask NAPA [the primary sponsor of the car] to allow him to drive again. We all agreed."
Waltrip is moving to a part-time driving schedule in 2010 so he can concentrate of his ownership duties at MWR. Martin Truex Jr. is moving to MWR next year and will have NAPA as his sponsor.
Terry Blount covers motorsports for ESPN.com.