) -- If you're looking for the best

deal on a used car

, some national auto search experts have a special message for you:

Cool your jets for 30 days and save 5%, 7% or even 15% on that car you really want.

Sure, by stalling, there's a risk in losing it. But the folks at

(who follow this sort of thing), say cars last on a lot longer than you might think, and that a little patience waiting on a used car can easily net you four figures in savings.

According to, an analysis of 30 million used vehicles shows that the price for many of of those cars and trucks were reduced by 7% before they were sold and driven off the lot.

Also see: Americans Are Late On Their Auto Payments>>

Since used cars are on

auto dealer

lots for an average 31.5 days, the strategy is simple -- if you have the patience: Identify newer used cars that just rolled up to the dealer; note the price; and come back every week for 30 days. By week four, the online car search firm says, the price of a used car costing $18,000 could easily fall to $16,800, saving you $1,200 in the bargain.

If you just can't resist temptation and don't want to lose the vehicle, that weekly visit should still result in a

lower sticker price

every time you visit the dealer.

According to, used car dealers cut the price on the average vehicle between one and six times over that 31.5 day listing period. The first price drop is significant -- the firm says that the price drops, on average, by 5% the first time the dealer rips the old sticker off the car and pops a new on.

Also see: Average New Car Price Up $618, Dealer Incentives Down>>

"The longer a car stays unsold, the more price reductions occur. Buyers should try to negotiate and use information like market value, length of listing and price drops in their negotiations," says Phong Ly, chief executive at

On a model-by-model basis, some vehicles see price cuts greater than 7% after 30 days.

Take a



300zx, which dropped 14.7% in the period it was tracked by Phong's firm. Or how about a


(GM) - Get Report

Cavalier, which fell in price by 13.7%?

Yes, waiting to buy your favorite used car using this strategy isn't fool-proof. But it does offer you a great potential deal: 5% to 15% off on a good used car or truck, just by waiting 30 days.