Personally, I never leave my vehicles to nobody....but everybody is different. I strongly suggest you to wait for your car at the dealership while your ride is being serviced. If you want to leave and pick it up later...I'd say no later than closing time which is 6:00 PM. Good luck!
Service department closes at 6 PM, but if you have spoken with your service advisor and you have paid for the service, sometimes they leave the keys at the reception desk and you can pick up your car. But be aware that the showroom closes at 8 PM.
Thanks! Your answer is awaiting moderation.