Beyond the legalities and beyond the immediate profit, you need to also look at the long term balance sheet. What is the cost of customer acquisition per vehicle sold in your place of business? In most dealerships this can easily be in the $500 - $1000 range. Make your customers happy and they will not only be a great prospect in the future, but they will also tell their friends and family about your honest business. Piss them off and they will surely tell everyone about your rip-off tactics. The difference being that honesty will result in much lower customer acquisition costs over time and dishonesty will always increase the cost of doing business no matter how you slice it.