I will be painting my car panther pink this summer. What color primer should be used under this? White? Gray? I am sure white would make the pink "pop" but what did the factory use?

you should use the recommended "shade value" by the paint manufacturer of your choice, if you decide to alter the "base", do a spray out of various tests, on different shade values to see what you desire

Check with your paint supplier. We use Dupont chroma premeir and every color has the correct sealer listed. Wrong sealer will cause color to be off, shading problems and require more coats to cover. I'd check with the paint supplier to see what color sealer is recomended. It doesn't matter what color primer you use on your body work. Car should be sealed before color goes on. Sealer color matters.

The closer the sealer color is........ The better coverage and less base color u will need before clear.

Sometimes. Viper red calls for white sealer. in Dupont. Thats why i say ask your paint supplier.