On my 99 GS400 I just had an aftermarket OEM spoiler installed at the dealer. I noticed that the shade of silver is slightly grayer or darker than the trunk lid. The service guy said that is because it is made of plastic rather than metal. He pointed out my rear bumper silver is a different shade than the rear metal panel because it is made of eurathane as well. He said that is normal on all Lexuses even the white ones that are brand new.

I am thinking, why would the material composition change the shade of paint? As long as you spray enought to cover the base color underneath it should match.

 

Hello. Let me tell you what my body shop guy told me when I got my TTE frt. lip,L-sportline rear,& Ugo Roof spoiler. If you have a trained eye look carefully at the frt,rear, bottom sides of all imports, japanese & European. You will notice that the latest cars & many older ones also have this appearances. I never really paid attention to it but, sfter my body shop guy me to look for cus good painters can see it very clearly. There are a couple of reasons for this.
1) Poly-Eurathane bumpers(plastic) blends & metal Aluminum stamp body panels looks different even when the same paint is used w/clear coat.
2) The paint is very hard to match but, good body shop should come very close. Metal chips. ex.(mettalic alpine silver) when painted on eurathane dries darker (more chips used darker the color) So they need to go with a lighter paint & use more chips than used on body to try to match)
3) It helps if the body guys use the same paint OEM
4) Darker colors Blk.Blue,Green easier to match.
5) Fiberglass kits dries & matches much better then eurathane.
6) When the car is assembled the bumpers come in already painted (Just in time process) . Same paint is used to match but,done some where else. Very noticeable on all Toyota cars including Lexus. Mitsubishi.
This is what my body shop told me, Hey he might be wrong.
I always thought that if you were to put down a layer of primer it shouldn't matter what surface it goes on because of computer matching that includes 3 different matches.

Paul