Red Bull let him go in less than two seasons, and Allmendinger had to fight every year for a ride and the track time to continue his development. The job of a lifetime finally came to him in late December, when Penske hired him to fill the seat that opened when Kurt Busch split with the organization.
It was the most prolific ride of Allmendinger's career, and both driver and team seemed thrilled with the pairing even as Allmendinger struggled at times in the No. 22 Dodge. He was 23rd in the Sprint Cup Series standings heading into Daytona, where he won the Rolex 24 Hours of Daytona sports car race in January.
The July suspension came at a time when Penske was evaluating picking up the option on Allmendinger for 2013. Sam Hornish Jr. was flown in to replace Allmendinger and will finish the season in the car, but Joey Logano was hired to drive it next season.
The next step for Allmendinger may be up to owners like Penske.
"He could be an option for us, for sure," Penske said before the IndyCar finale at Auto Club Speedway on Saturday. "He's someone we would consider. This is a speed bump in his career, but he's certainly an option for people on the NASCAR side and the Indy side."
Allmendinger said Tuesday he was grateful for the support he's received from Penske the last two months.
"It was great to go to the IndyCar race and he's been amazing and such a great friend through this, and he's the guy I always wanted to please and my biggest regret is letting him down," Allmendinger said. "I was always afraid to ask him for advice before, and when you've got everything taken away from you, your guard gets let down.
"Now, I'll always turn to him."
Penske doesn't have an open seat in NASCAR, and it's not clear what will happen with his third IndyCar team. He's already picked up the 2013 options on Will Power and Helio Castroneves, but has told Ryan Briscoe he's free to look around while the team tries to secure sponsorship for that seat.
Allmendinger was the second Sprint Cup Series driver suspended under NASCAR's tightened drug policy implemented in 2009. Jeremy Mayfield was the first and he unsuccessfully sued to have the results overturned. Court documents showed that Mayfield tested positive for methamphetamine.
Allmendinger believes his situation is different.
"It was the biggest mistake of my life. Stupid mistake," he said. "But it's not going to happen again and the people who know me know it was a mistake."