Generally, I agree - how would any car company or dealer know you flipped at all? But in the rarified air of certain brands, they don't prevent you from turning around and re-selling, they simply blacklist you.
My wife owns a $15,000 Birkin - she told me if she resells it and the purse comes back for re-conditioning at an authorized Hermes dealer and she is not the owner when they run the serial number, her name goes into their database and she is blocked from buying Hermes products in the future (oh, the humanity
- this is actually better for our bank account). It used to be that you were only blocked at a single location but the Hermes brand was being diluted by flippers so frequently, they instituted a dealer-wide serial number network. People can, and will, flip these bags for 2x their value. Hermes doesn't need their future business, it isn't a "mass-produced" consumer brand, so they will simply blacklist the holder of the flipped serial numbers. Consider Ferrari - you can wave a blank check and you will still never be able to buy certain models. Their rarity and cost ensures their ability to simply say "no".
The question, really, is whether Grenadiers are exclusive, and coveted enough to be able to do this. Mercedes G63 models can run $340K so the answer there is "probably yes." For Grens, I would imagine flipping will happen in every one of their markets - look at the Autotrader posts in EU to see it happening in real-time.