Unfortunately these systems permit only a search for that particular manufacturer's product line. The search begins with a dealer entering a password, the product code, color, and equipment. The search will tell the dealer what cars are available, the name and location of the dealer that has the car, and pricing information. Normally the dealer can have the car for you in 24 hours or less. You should not be charged to have the car you want DX'd.
Dealers prefer to sell out of stock first.
If your salesperson does not have your car in stock, most will suggest they do a locate for a match or a car very close to what you want. The salesperson will call the dealer listed as having the car to verify its availability. If you want to buy the car, the salesperson will arrange to DX or dealer exchange for the car. Usually the salesperson that's making the sale will drive to the other dealership and pick up the car. The dealer with the car does not have to give it up.