Cadillac’s XTS Platinum concept car introduced earlier this year at the North American International Auto Show in Detroit might have looked and felt like a flagship model, but the crest-and-wreath brand apparently has another card up its sleeve.

General Motors CEO Ed Whitacre Jr. has reportedly green-lighted a larger and pricier Cadillac flagship – one that could compete more seriously against the likes of Mercedes-Benz’s S-Class.

To compete in that segment, Cadillac knows it would have to offer rear and all-wheel-drive. The XTS, set to debut for the 2012 model year, shares the Epsilon II platform with the Buick LaCrosse. It’s unclear just what GM would do for a range-topping rear-drive sedan platform since it doesn’t currently have anything suitable in its portfolio beyond the Sigma platform that underpins the CTS (Sigma II) and the lame-duck STS (first-generation Sigma).

GM does have a number of suitable powertrains for a larger vehicle, including the 6.2-liter V8 from the CTS-V. The XTS is likely to debut with only naturally aspirated and twin-turbocharged six-cylinder powertrains.

Look for the S-Class-rivaling Cadillac to debut for the 2014 model year.