Good evening all,
New to the forum and new to this precision instrument of the road/ track that is the S2000. I just purchased a 06 Rio w/ 19k on it 2 owner, clean car fax. I have the very same problem, my bumper colors are off as well and certainly more noticeable in certain lights, all vin numbers match and nothing looks to be off. I believe/ hope this is normal.

 

I as well, 2005 Rio with 34K miles and the front bumper looks almost like the other yellow-much lighter. Clean carfax but I am missing the vin sticker so obviously it has been repainted and poorly done too-paint is flaking off in certain curvy areas revealing primer or bare bumper. Was gonna have it repainted but not sure now since it appears to be so hard to match anyways.

 

i just got hit today in the parking lot and some backed into my car while i was in it and hit my door (i was not moving so all her fault). I dont wanna go through paint matching again, it sucked last time. They had to repaint it 3 times until it got close enough and now i have to do that crap again.

 

Rio is much easier to match than Spa. Since you're looking at an 08, it'll be Rio as opposed to Spa.
Spa 00-03
Rio 04-09