NHTSA documents discovered by GM Inside News reveal Buick will expand its Avenir subbrand in 2018 with the addition of the LaCrosse.

As the full-size sedan market continues to crumble, and the LaCrosse carries a production crippling 204-day supply of inventory, Buick will push its flagship sedan further into the premium sphere as it attempts to chase unsatisfied luxury shoppers with its new top-shelf Avenir line.

The information comes from GM's 2018 Vehicle Identification Number Decoder which the company revised and submitted to the NHTSA late last month. As denoted by the VIN's fifth position Buick plans to offer the LaCrosse Avenir in both front and all-wheel-drive configurations, likely paired exclusively with the existing 3.6-liter V6 and GM's nine-speed automatic transmission.

Expect the LaCrosse to gain visual cues similar to the recently launched Enclave Avenir: Buick's new Evonik Acrylite LED lighting system will don the front and rear fascias, along with a new three-dimensional grille flanked with Avista-style chrome wings, along with Avenir exclusive wheels.

Inside the LaCrosse Avenir should get new color choices, accent piping, contrast stitching, embroidered front headrests, a wood-trimmed steering wheel and Avenir branded door sills.

Like the Enclave also expect Buick's full suite of safety and tech features like adaptive cruise control, forward automatic braking, rear cross traffic alert, pedestrian baking, lane keep and departure, a vibrating safety seat, and 360-degree surround vision. Tech wise, look for an 8-inch infotainment screen with nav, wireless charging, Apple CarPlay and Android Auto, OnStar 4G LTE Wi-Fi hotspot, and probably another application of GM's rear camera mirror technology. Oh, and there might even be an air ionizer.

Using the $5,400 price difference between Avenir and Premium trim Enclaves, it's likely pricing for the LaCrosse Avenir will start north of $45,000.