Brad Keselowski tests Team Penske Indy car at Road America

Describing it as “one of the best days of my life,” Brad Keselowski participated in an Indy car test Wednesday at Road America, taking at-speed laps around the four-mile Wisconsin road course.

Keselowski, a full-time NASCAR driver and the 2012 Sprint Cup champion, was in attendance as Team Penske took part in the scheduled test. In addition to fielding NASCAR teams for Keselowski and teammate Joey Logano, Penske also runs four cars full-time in the IndyCar Series, the premier North American open-wheel tour.

“I’ve always wanted to drive an Indy car, I think (Penske Racing President) Tim Cindric knew that,” Keselowski said, according to IndyCar.com. “The opportunity came up to dip my toes in the water and kind of expand my knowledge base and put it in the back of my mind for wherever it goes, I don’t know. But it was a heck of an opportunity and I’m glad to have a chance.”

The test-drive came to light via Penske’s Twitter feed, which began posting photos of the session mid-afternoon. It wasn’t disclosed how many laps Keselowski completed nor his exact lap times, just that he trimmed 10 seconds off his time from beginning to end.

Keselowski drove the No. 22 Chevrolet-powered Dallara of Simon Pagenaud, the IndyCar points leader. Pagenaud shook down the car before Keselowski got behind the wheel.

“First thing I told Simon is he has a very secure job, at least from me,” Keselowski said. “I’ve got a lot of respect for him and his team, everyone at Team Penske.

“Simon was fast, really fast and gave me a good rabbit to chase. I learned a ton today and had a lot of fun. I’ve got to let it soak in here to think about all of it.”

Wednesday wasn’t the first time Keselowski turned laps at the fabled road course located in Elkhart Lake, as he finished fourth in a NASCAR Xfinity Series race in 2010. The differences between a full-bodied, bulky stock car and a much more nimble Indy car didn’t go unnoticed.

“(The Indy car) sure was getting in the corners a lot deeper,” Keselowski said. “I think the Indy car just pulls so many G’s through the center of the corner and in the brake zone. You have to build confidence in it because the stock car does everything it can to wreck your confidence and in the Indy car it’s important to have confidence. So you have to kind of unlearn everything you learned in a stock car to be good in these cars. That’s a heck of a process but a fun one.”