I did this weekend. The dealer provided me a link to sign up for the credit card which gave me $500 credit towards the car, then I used the card to charge $3000 of the upfront payment. This was the maximum that the dealer would allow. The new card is 0 percent interest for 9 months so I’ll carry that balance and pay it off just before that expires.
I won’t know until my statement comes but I should get 7x points for spending at GM, (4x everywhere else). Additionally there’s a 15000 point sign on bonus that I should get for spend $1000 on the card. I don’t think that is sacrificed by getting the $500 rebate, but it might be. That would be worth $150 towards service of my car.