There are also plastic-specific primers. I don't know the SEM products as my truck isn't, erm, show quality
When I did my panels I just used the Krylon and such from the local Ace.
One thing I can offer is that, as with all things paint, it's all about prep, prep, prep. Surface condition is key. In my case, I had mismatched door panels, so I got a junkyard pair that matched ... but apparently had been stored three inches from the sun's corona.
I spent considerable time lightly sanding them until the gritty outer sun-damaged layer came off. Then it took several light coats of plastic primer before the surface was nice again.
Since then I've had a bit of flaking, on the corners where I didn't sand so much and in spots where grease and dirt had accumulated. The lesson there is surface prep, and degrease, even with just like water-down 409 or the like.
I also found that the spots that flex, in my case by the window cranks, and maybe the pulls, are prone to cracking. Extra prep and careful application of the final coat (color or in my case matte clear) is prolly best there.
Pix and more rambling on my build thread @
https://ck5.com/forums/threads/74-k...to-why-you-do-that.209791/page-9#post-3016041
-- A
