Don't wait. By Fall VW will have likely met it's 200k vehicle sales as Audi us included in equation. Bye bye 7500k Tax Credit.
No, I believe it is done by "name plate" or make, not buy corporate owner. VW is separate from Audi for purposes of the rebate.
VW of America, Audi of America, and Porsche North America sales are not
all lumped together for purposes of the tax credit because they are all subsidiaries and separate business entities in the U.S. They are all owned by Volkswagen AG (VAG), but considered to be separate manufacturers for puposes of the U.S. federal tax credit.
It comes down to the legal difference between a subsidiary and a division of a larger company. A division is a part of a larger business entity. This means that a division, although it operates in a different name, is still a smaller piece of the larger entity itself. On the other hand, a subsidiary is an entirely different company that is owned by another, usually bigger, entity.
As a contrast to the VW/Audi/Porsche situation, consider Lexus vs. Toyota of America. Lexus isn't a subsidiary, but rather a division of Toyota of America and thus not a separate business entity. Therefore, Lexus and Toyota brand EV sales are all lumped together under the single manufacturer (Toyota of America) for purposes of the tax credit.
By the way, here's the official information about what vehicles are eligible according to the IRS:
IRC 30D New Qualified Plug-In Electric Drive Motor Vehicle Credit | Internal Revenue Service
And by the way, the tax credit gradually phases out over a period of time after a manufacturer has passed 200,000 cumulative sales. VWofA sold less than 20,000 e-Golfs in the U.S. between 2015 and 2019. Add just over 17,000 ID.4s last year and their cumulative U.S. EV sales are now around, say, 36-37k. Let's be optimistic and say they triple ID.4 U.S. sales in 2022 to 51,000. So at the end of 2022, let's say they're around 85-95k cumulative sales. In 2023, they'd have to sell over 100k EVs in the U.S. for the tax credit to start to phase out. With the Chattanooga plant coming online for the 2023 MY, that is definitely a realistic possibility, but who really knows what the production numbers will be there? This is just me speculating, but I don't see the tax credit for VW EVs to begin phasing out until late 2023 or early 2024 at the earliest.