There is a bunch of rules so that no rider can have any physical contact with the support or pilot car while on the road, and the car has to be behind the rider so that the rider can't try to draft off the car.

Travis I suppose would be the ultimate source on this, but I think the support vehicle can stage riders every 5 miles. When the rider comes up to the pass-off the new rider gets up to speed, tagging the new rider is not necessary only an overlap of the front/rear tire for a second to count. The old rider then hops in the support vehicle which moves into the next position for either restocking the rider with food/water or next rider drop-off. Support vehicle and pilot vehicle can be the same on the 200, but on the 400 there has to be two, since the pilot car always has to follow the rider, but that's only for the hours of 12-5am after which point it can do double duty again. Though I would guess on these longer relay races you would want two cars most of the time anyway just to keep an eye on the rider and also get the next riders ready.

I was thinking about doing the 200 mile as a solo event, I mean still ride with people but not do it as a relay. The 400 would be pretty rowdy though it'd take me a solid 30 hours to complete, if I could complete it at all.