we have all heard of the Buick GN / Grand National, but I hadn't heard of the twin, the Regal WE4 until now

only 1,547 WE4s were produced.

The only differences between a WE4 and the Grand National were the interior color, aluminum wheels, exterior badges, aluminum bumper supports, and aluminum rear brake drums,

as opposed to the Grand National’s rear spoiler, cast-iron drums, and steel wheels and bumper supports, making the WE4 basically a lightweight GN.

https://www.hotrod.com/articles/readers-ride-1987-buick-regal-we4-turbo-t/