I wouldnt reccomend using a primer sealer for your stripe on a new car.
Go get PPG's DCC single stage and have them mix in some flatening agent , as they know how much to formulate to get that satin finish you want, you will still have to catylize it , but it will last.
I would think a quart of black , and a pint of catylist and some reducer would be enough. it will also be compatiable too.

Dont slack for cheap on a new car.
Do it right the first time !

SprayTech