One old chestnut of car-buying is that a new car's value plummets the second you leave the lot — and therefore, you can save some money buying a mildly used car. In many cases, that is true — the average new car has lost about 17 percent of its value by the time it's a year old — but it's not true with all cars.
With some vehicles, it takes a while for the depreciation to kick in. For those cars and trucks, rather than buying used, you're better off heading to the dealer for a new one.