Used car prices could go up 4% to 6% in 2012, which means buyers sitting on the fence may want to start shopping before prices escalate.

The price increase will come after several months of declining prices in 2011, according to a recent report from Kelley Blue Book.

Since peaking in June, used vehicle values have declined 10%, a result of automotive market cooling due to cheaper gas prices and the end of supply constraints for Japanese automakers. In October alone, prices decreased 2.6% overall.

"Considering the already significant declines in used-car values since June, Kelley Blue Book predicts that values will decline an additional 3 to 4 percent by the end of the year," said Alec Gutierrez, manager of vehicle valuation for Kelley Blue Book.

Used car prices usually drop at the end of the year, Gutierrez said, due to a drop in demand that lasts through the holiday season. This year should stick with that trend, he said.

The good times, however, won't last. KBB projects used car values bouncing back significantly in the first quarter of 2012.

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"Since 2009, used-vehicle registrations in the first quarter have increased by 15% to 20% on average from the preceding fourth quarter, and since we expect a similar increase in demand in 2012," said Gutierrez.

That's partially because of the financial crisis in 2008, when leasing all but disappeared. Cars that are returned at the end of a lease go into the used car market -- and because leasing declined in 2008, there are fewer cars coming into the used car market today.

Used car values historically rise in the first quarter of a given year, so it's going to be in the consumer's best interest to buy before 2012. You could save some significant coin.