A car salesman who says "I can't hold this car for you if you leave" is a liar trying to pressure you into signing on the dotted line without having help reviewing the contract.
FTC press release:
Not all dealers play by the rules. In a case announced today, the FTC alleges that Tate’s Auto Center of Winslow, Inc. — as well as related dealerships in Arizona and New Mexico and their owner and manager, Richard Berry --
* used deceptive advertising to get people in the door,
* failed to disclose required financing terms, and
* frequently falsified consumers’ income and down payment information in an effort to close the deal.
Instead of using the income information people gave, Tate’s often inflated numbers to make it look like people had higher monthly incomes.