Fiat driver Jonathan Start is the 2012 Pirelli World Challenge Touring Car B-spec series champion, wrapping up the title in his Fiat 500 at the season finale at Sonoma Raceway.

Start finished fifth in Sunday’s 40-minute timed event after posting two fourth-place finishes in Saturday’s back-to-back, 25-minute race to clinch the title at the 12-turn, 1.99-mile road course in Michigan.

Tim Kuniskis, head of the Fiat brand for North America, Chrysler Group, said: “The solid engineering behind our Cinquecento is not only able to successfully compete in Europe, but also to win titles in America.’’

Start said he was excited with his championship win, but it didn’t come easy. “We kept our Fiat 500 clean and did what we needed to do to claim the championship. With all the tight turns, elevation changes and slow corners, it was another learning experience for us,’’ he said.

Modifications for racing in the series are limited to shocks, springs and the required safety equipment.

“It’s been a great first year for the Fiat programme,’’ said SRT Road Racing Manager Gary Johnson. “Start drove smart all year and focused on the title rather than individual race wins. It takes a real professional to look long-term, race clean and finish every race,’’ he said.