The OSU police have several unmarked vehicles. An older model white Dodge truck and an older model white Tahoe I think. And they are GOOD. I've tried finding the lights and couldn't, even though I knew they were there. I never would have known about them if I hadn't seen them respond to emergencies on campus.
I don't agree with it either...especially for a campus PD.
If you are talking about the same vehicles that I am thinking about they are EHS vehicles that respond to emergency calls. They have 2 Dodge Durangos, Wht Dodge Dakota and a Full size van. I believe all of the campus police vehicles that would pull you over are marked although there are a few unmarked.