I am almost positive that there is a gps locator on my car. I have an infiniti I30 2000.?

Can someone please tell me where one might hide one of these on my car? I have looked under neath my car, not completely.. But a cursory glance and could not see anything obvious.. What exact shape am I looking for and where would someone typically hide it that would be a good hidin. Not sure if this is pertinent.. But I am quite sure it is not the authorities.. Because I would find it hard to believe that they could ascertain a court order for more than a year. Otherwise.. It is illegal for a civilian to do this which is why I need this proof.. Please help me.