Mercedes E350 Retired Loaner - Stack with Costco $1000

Greetings all. Working on deal for a 2500 mile 2020 E350 loaner. I know that all new car Mercedes Promos are applicable but can I stack the $1000 Costco on top? I assume so since the car was never registered. Responses appreciated.

Yes. However it wouldnt stack with the Fleet discount.

Thank you!

Have you verified the rest of the deal is good?