For down payment, you can use whatever the dealer will take, but he should be able to take a personal check...Mine did. But Staggie's absolutely right on this one. If you use a check or cash for a deposit to hold the car and for whatever reason the deal falls through or you aren't happy with the dealer and want to take your business elsewhere, kiss your moola goodbye. I've never put a deposit on a car. If you're serious about buying it and you have some kind of credit, the dealer should hold it for a day or two, if he's a good dealer. If he's a scumbag, then I'd tell him Buhbye.