I like Griots ceramic 3-1 wax spray for the paint and griots ceramic trim restore for the plastic, it gives the plastic a deep black with a satin look so it's not too glossy
Ditto the Griots 3n1. I can't say what the dealer did as far as washing while on the lot (mine was on the showroom floor so hopefully it was washed less than one that sat outside), but since I purchased the vehicle new, my car has never seen a car wash. My routine is as follows:
1. Pre spray car with ONR. 2. Using a solution of 128:1 Water/ONR, I wash 1 panel at a time with Big Red Sponge and ONR solution. 3. I dry immediately with Big Red Towel.
If it hasn't rained in awhile, or the car is super dirty, I'll do the above but instead of the ONR pre-spray, I use a foam cannon and soap up the entire car using Maguires Gold soap. I don't use a rag here, just let it sit a bit then hose it off and then do the above.
Every 4-6 months, I use Griot's 3n1 Ceramic wax. In between, I use Griots Ceramic Speed Shine. I haven't needed to clay bar.
For the black plastic exterior and interior dash and trim that is non-leather, I clean with ONR solution (it's fantastic) and then use 303 Aerospace protectant. It doesn't restore faded black plastic but I've used it for years and my interior and exterior plastics never got cloudy, faded or turned color. I use either Griots Leather all in one or Lexol leather cleaner and their conditioner on the leather seats and trim.
My paint is super smooth and no swirl marks. The water beads like crazy when it rains.