It isn't as far as I know. The dealer can put in writing (sales order) what he/she will sell a car for but it doesn't obligate the consumer. Most of the time when the dealer doesn't put it in writing they can back out of the deal. Putting it in writing only obligates the dealer. Until the contract and financing go through the buyer is not obligated. Let's face it... if you haven't paid money for the car already, can anyone really make you buy it?