Around here they are called "Base Performance". They've not been available as a new custom order -- only SR+, LR AWD, and Performance (w/ brakes, 20", spoiler, etc) are -- but theyve been prolific recently in inventory.
They are/were not strictly tied to anything whether 18" or 19" wheels. They are/were freely configurable with the other options such as colors, fsd, tow-hitch.
I tried to buy one directly from the website, which went to my account... then the sales dudes called me and told me that that specific car (vin) was a "mistake" and somehow not available. then i slowly watched as the inventory dwindled down (of all cars, not just the Base Performance).
recently the inventory was refreshed against, but with mostly SR+. the Base Performance vehicle is still in MY account. the sales people havent told me whether i should cancel it; make a new order; or to anticipate that replacements will be made that i will be matched to.
such is the fun process of buying car from this company....