The Cadillac, code-named XTS, is expected in 2011 and will replace the front-drive DTS and rear-drive STS, the sources say. The X in the code-name suggests that all-wheel drive will be optional or standard.

The car is part of an emerging strategy for Cadillac that mirrors BMW’s three-car lineup of small, medium, and large. The CTS would be the medium-size car, and a new small Cadillac also is expected in 2011, sources say.

GM has made little secret of the new flagship, showing a drawing of the concept to dealers at a meeting last month in Detroit. Details are emerging about its platform and production site.

The new flagship may be assembled at GM’s Oshawa, Ontario, plant, the Canadian Auto Workers union says.

GM told the CAW last month that the Oshawa plant will be getting two new midsize sedans, says Chris Buckley, CAW Local 222 president.

While the specific models were not revealed to the CAW local, “there is a very real possibility that a Cadillac will be built in the city of Oshawa,” Buckley says.

Oshawa will produce a hybrid, short-wheelbase sedan in the first quarter of 2011, and a long-wheelbase sedan will go into production in 2013, said Jennifer Wright, a GM Canada spokeswoman. She declined to reveal the brand of the new models.

The Cadillac sedan will be developed on GM’s new global midsize vehicle platform, industry sources say. The first U.S. vehicle developed on that front-drive platform is the 2010 LaCrosse, which goes on sale this month.

But sources say that platform will be modified, creating a car that is 1.5 to 2.0 inches wider than other vehicles developed on the same platform. The LaCrosse is 73.1 inches wide, already about a half-inch wider than the CTS.

A source says Cadillac wants the cabin comfort that buyers expect in a luxury vehicle. Overall, the Cadillac sedan will be about 200 inches long. By comparison, the redesigned 2010 Mercedes-Benz E-class sedan is 191.7 inches long and 75.9 inches wide.

Still to be determined is whether all-wheel drive will be standard or optional on the Cadillac XTS.

The Oshawa car plant produces the Chevrolet Impala and the Camaro on separate lines. Buckley says the line for the rear-wheel-drive Camaro is flexible and can assemble rear-wheel and front-wheel-drive vehicles.

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