GM engineers are finally done with Nurburgring and Germany and are going back home to prepare for debut of the Cadillac ATS at Detroit Motor Show early next year.

The new sports saloon will be among four General Motors’ concept or production vehicles making world premieres at the 2012 North American International Auto Show in January.

Cadillac has been relentlessly testing the car at the ‘Ring because they are determined the ATS must be on the par with the BMW 3 Series handling-wise. It’s going to be the best sorted American chassis ever. It has a new rear-wheel-drive-based architecture designed for agile, quick-and-fun driving dynamics and advanced technology. The ATS goes into production next summer at the Lansing, Mich., Grand River Assembly plant.

“ATS is a crucial part of Cadillac’s expansion,” GM Senior Vice President of Global Product Development Mary Barra told the Automotive Press Association on Friday. “ATS enters the biggest market segment in the global luxury car industry, both in terms of volume and importance.

“It’s a segment dominated by German cars, including the BMW 3-series, Mercedes C-Class and Audi A4, so we’ve developed a compelling and convincing new challenger,” she said.