Carpentier said:

It’s been a few years that I’ve thought about it. I discussed it with my wife. We talked about my situation on several occasions and I came to the conclusion that I must move on.

Carpentier made his NASCAR debut in what is now known as the Nationwide Series in 2007 at Montreal’s Circuit Gilles Villeneuve driving the No. 9 Gillett Evernham Motorsports Dodge. He started on the pole and finished second. He made his Sprint Cup Series debut eight days later in GEM’s No. 10 Dodge at Watkins Glen International. He started 40th, led seven laps, and finished 20th.

He made four more starts that season, two in Nationwide and two in Cup. He finished 19th in the Zippo 200 at Watkins Glen and 42nd in the Ford 300 at Miami-Homestead Speedway in Nationwide. He finished 33rd in the Checker Auto Parts 500 at Phoenix International Raceway and 40th in the Ford 400 at Miami-Homestead in Cup.

In the fall of 2007, it was announced that he would run the No. 10 full time in Cup in 2008. He made 24 starts in ’08, averaging a finishing position of 29.6.

He also made eight starts in the Nationwide Series for GEM. He posted four top 10s, including a runner-up finish at Montreal. And, he made on Camping World Truck Series start driving for Bobby Hamilton Racing-Virginia in the O’Reilly 200 at Bristol Motor Speedway. He finished 25th.

In the summer of 2008, Carpentier announced he would be leaving GEM after they hired Reed Sorenson for 2009. In October, he was released by GEM and former Red Bull Racing driver AJ Allmendinger finished the year in the No. 10.

In 2009, Carpentier drove Michael Waltrip Racing’s No. 55 Cup Toyota at Infineon Raceway and Watkins Glen International. He also made three starts in Tommy Baldwin Racing’s No. 36 car in events that conflicted with Mike Skinner (TBR’s full-time driver) Camping World Truck Series schedule. He finished 11th in the Toyota/Save Mart 350 that year, his best career Cup finish.

In 2010, Carpentier ran six races for Latitude 43 Motorsports, replacing David Stremme who left the team, claiming owner Bob Jenkins was not interest in helping the team improve. He never finished better than 21st.  Latitude planned to run select races in 2011, but they have yet to make a start. They are believed to have ceased operations.

Carpentier also ran one race for MWR, the Nationwide race at Montreal. He finished 32nd.

In 2011, Carpentier ran FAS Lane Racing’s No. 32 in the STP 400 at Kansas Speedway. He started 40th and finished 30th. 

Carpentier’ saw his most success in the CART Champ Car Series between 2001 and 2004. He won at least one race in each of those years while driving for Forsythe Championship Racing.

Carpentier left Forsythe to join Cheever Racing, Eddie Cheever’s Indy Racing League IndyCar Series team, in 2005. Carpentier never won an Indy race, largely due to uncompetitve Toyota engines used by Cheever Racing. The team lost its sponsor, Red Bull, and Carpentier was left without a ride.

He attempted to qualify for the 2011 Indy 500 driving for Dragon Racing in the IZOD IndyCar Series. He failed to make the race.