Is it bad to have this many materials?

I have 4 materials, pretty small res per human model. Is that too much, how bad is that to do? I don't have time to UVW map so I do it like that... and also because my game is based on models being multi purpose as in interchangeable like in Borderlands... and they need to be able to change colors part by part basis. So yeah, will that kill the cpu? The game is open world and rather complicated coding wise. Like vehicles are somewhat realistic, many weapon types etc. Poly count for player model for example is 2000 +... So yeah, 4 materials for a humanoid model with low res like 512*512 texture size. Is that too much? Can I push it to more? Need to know... Thanks.