As Adam says above, if it is inside the car and not bolted down, it is a loose item. Now we could get silly and say that carpet is glued not bolted, but I think you get the idea. The reason for this rule is that in the unfortunate event of an impact, loose items become projectiles and anybody in the car, Driver or Instructor are put in additional danger. Now I doubt anyone will get mortally injured from a flying Tissue Box, but a Mobile Phone could easily become more than a distracted driving hazard. Heavy items inside the glovebox can also come hazardous if the door pops open in an impact.
I do not believe that properly installed OEM carpet mats in the drivers footwell are a problem, it is the aftermarket loose mats that pose the real risk of bunching up and getting caught under the pedals. The caveat here is ‘properly installed’ with secure fasteners. Not sure if Velco comes under that heading, but if it is OEM and the mat is not able to move without purposeful pulling, it is probably OK. To respond to Larry’s issue with his passenger floormat, you really shouldn’t have to remove that at all. It is not a pedal hazard and if it is that hard to get out, it is not a loose object risk. Likewise hats and light clothing stuffed behind the seat on the floor are not really a problem, although entire wardrobes are certainly not encouraged.
Suction Cups and the fasteners used on those 407 transponders may seem like a secure mounting, but they are not. For lightweight objects like the transponder the risk is low, but GPS and some Cameras are quite heavy and the vibration, especially on cars with modified suspension, can easily cause them to come loose.
Ultimately it is the Tech Line and Staging area personnel that will decide what is acceptable and what is not. Protests wrapped in a $100 bill can be forwarded to the Track Team if you don’t agree!