Buick did a bad job hiding the fact that a brawny GS variant of its 2018 Regal Sportback is on the way. It accidentally teased the vehicle's presence on its Canadian website earlier this month before attempting - and failing - to remove all traces of this nugget from the internet.

Well, thanks to the California Air Resources Board, we now have documented proof of the GS's return. The go-fast Buick will bow as a 2018 model, perhaps concurrently with its liftback and wagon siblings, but don't expect any drivetrain similarities to the outgoing model.

The emissions document covers a host of 2018 General Motors passenger cars outfitted with 3.6-liter V6 engines. As the lesser Regals see only a turbocharged 2.0-liter four-cylinder (in two torque outputs), the 3.6-liter "Regal AWD" listed here can only be the GS.

This GS breaks with the current model in several ways. This time around, it looks like GM isn't in the mood to offer buyers much choice. The only transmission available is a nine-speed automatic, which means the save-the-manuals crowd can add Buick to its list of automakers no longer fielding a stick shift.

Oddly, the nine-speed gearbox is only found on front-wheel drive variants of the 2018 Regal Sportback and TourX. As the document states, four-wheel motivation comes standard on the GS, unlike the choice offered by the previous generation. Buick's AWD system features torque vectoring for improved performance.

While the document doesn't dish any details on engine output, the same engine makes between 305 and 335 horsepower in other applications. For the GS, it's possible GM could raise that power ceiling.

One thing that isn't too mysterious is what the GS should look like. The China-bound GS was revealed last week ahead of the Shanghai Auto Show, sporting a body kit, chromed air inlets and larger, blacked-out wheels. Unlike stateside customers, Chinese buyers will have to make do with GM's turbo 2.0-liter as the sole engine offering.