Quote:

It is commonly called "radio delete" when there is no radio ordered for the car.



But it is misleading. Like you say, it is the accepted form of describing a car ordered without an optional radio. I don't know why this term is so popular to use, seeing you never hear a car referred to as a 440 delete car, or a power window delete, or a whatever optional equipment delete. It just doesn't make sense. But people seem to be in love with the way it sounds so best just to accept it and move on.