The USA Pro Challenge

Sunday I went to see the finish of the USA Pro Challenge, a series of bicycle races that took place this past week throughout Colorado.  The race yesterday featured individual riders trying to finish with the fastest time.  At each curve, an official would first blow a whistle and wave a flag.  Then a police motorcycle would rush by, followed by the bicyclist, who in turn was followed by a speeding SUV, supposedly the rider's support vehicle.  I looked inside one of these "support" vehicles as it passed.  It appeared to be filled with laughing, partying teenagers.  Is this really a "support" vehicle, and if so, what kind of support do they provide?  Or are these simply random teenagers who put advertising decals on their cars and then sneak onto the track behind the riders?  If so, there ought to be a law.