I'm the third generation in my family to be in the new-car business (for the same dealership and I campaign the dealership's last NHRA Stocker) and can tell you with both honesty and certainty that we never used the bait-n-switch tactic. We would order a base model car with zero options and advertise that specific car at dealer cost to attract buyers. Perfectly legal and nothing underhanded. That advertisement clearly listed what the car was and also listed the VIN and the amount of cars available at that price. Absolutely nothing deceptive and when a customer inquired about that car in the ad, they were directed to it as normally, it was on the showroom floor with the ad affixed to it. More often than not, it took some time to sell because of the lack of optional equipment. When it was sold, we'd pull the ad, and replace the car with another ordered with zero options. Lawfully, a car couldn't be advertised unless it was in stock and readily available for public consumption. As for Stock numbers, we tried several methods of internally identifying the inventory, ultimately using the last eight digits of the VIN as the year indicator was included. Prior to 1980, we used a system with the year and what number chronologically that specific car hit the lot.