I know that trying to buy one of your own cars sounds like a huge waste of time, but you just might learn something about your dealership and its buying process. You may find that you have some ridiculous policies that only make the process slow and tedious. Or, maybe you find out that it asks you for your driver's license information three separate times - wasting the customer's time and, in the long run, pushing the customer away from your dealership.
There are many things to be learned from this simple task. To go even further on this, try submitting an Internet lead to yourself. Again, you may learn that you're directing calls to the wrong receptionist. All these things will only discourage your customers from coming back to your store. The customer expects you to spoon feed them - so the first sign of something going wrong, they tend to freak out.
The best thing is to just make sure that everything runs as smoothly as possible. This ensures that the customer is very comfortable and enjoys the buying process. So, please give this best practice a try and see if it doesn't teach you something about your store and its buying process.