The RVI Group out of Stamford, CT has a prediction: now is the time to buy a used luxury mid-size sedan like the BMW 3-Series, Lexus ES, or Audi A4. Prices will jump upwards through 2013 before declining slightly in 2014.

It's a drum I've been beating a lot this month, but December is a great time to buy any used car, but especially a luxury mid-size used car. According to RVI, luxury mid-size sedans have seen a slight downturn since October. RVI's Used Vehicle Price Index shows a small decrease from October (-0.6%) while Manheim (another group that tracks used car sales) shows a 2.2% decrease.

Prices are soft in this segment because supply has been increasing as vehicles come off lease. RVI said in its 3rd quarter report, "Our Used Vehicle Stock Index points to a 73% increase in used vehicle supply for 2009, but is expected to significantly decrease beginning in 2010. Our Competitive Index points to an increase from the current level suggesting that competition and incentive activity will continue to increase through 2012 decreasing thereafter. We estimate that values for Luxury Mid-Size Sedans will steadily climb through 2013."

Act now. Don't come complaining to me in 2010 that you should have bought that used BMW 328i or the 2007 Audi A4 (pictured above) when you had the chance.

Photo © Audi

Bloomberg News reports that new car deliveries will climb to 12.4 million from 10.3 million in 2008, the Ann Arbor, Michigan-based Center for Automotive Research said. U.S. sales were 13.2 million last year, after averaging 16.8 million this decade through 2007. So, why is that important to you as a used car buyer? It means additional supply for the used car market.

More new car sales mean more cars being traded in that end up in the used car sales lots. It's supply and demand. More supply means lower prices (or at least stable prices). This all means 2010 could be a great time to buy a used car (unless of course you buy a used car before the end of December).

There's an interesting tidbit in the article: "Cars on U.S. roads ... now average a record 10.5 years old, and the sales rate has fallen to 42 autos for each 1,000 adults, Center for Automotive Research chief economist Sean McAlinden said. In the 1992 recession, the rate was 66 autos per 1,000 adults, he added.

Factor all that in and it means good things for the used car market in 2010.

Interesting statistics on the used car market from an article at AutoRemarketing.com written by Joe Oversby. He obtained statistics from ADESA, a leading provider of vehicle remarketing services that show wholesale prices should continue to show "stable-to-firming" trends in the near future.

What that means for you as a consumer is used car prices are not going to be dropping in 2010 - nor should they be going through the roof. Demand is going to be tight for particular models, which means you might have to settle for something different than you originally wanted.

Among the facts reported in the article:

• The average wholesale price in November was $9,519, a 9.3-percent year-over-year gain and a 0.6-percent upswing from the previous month.
• The Bureau of Labor indicated that the used vehicle consumer price index was up 2.3 percent year-over-year in October -- which is the most up-to-date government data available -- and this marked the first year-over-year jump in the index in 16 months
• Average prices for trucks were up 15.7 percent from November 2008, while car prices climbed 3.7 percent from a year ago.
• The retail side of the used-car market saw a 34.2-percent increase in sales from the prior month, which helped to mute the 41-percent decline in October
• Certified pre-owned sales dropped 18.4 percent year-over-year and were off 14.3 percent from October.

There is a report out from TrueCar.com about the best days of the year for buying new cars. However, if you're in the market for a used car and you're buying it from a new car dealer, this info will help you determine the best days to buy a used car. You better act fast because six of the days happen before the end of the year.

These are the days and the correlating expected new car discount. (I see no reason you can't expect the same discount for used cars because those sales reps face the same pressures as new car sellers.)

• Dec. 24 7.25%
• Dec. 21 7.13%
• Dec. 31 7.04%
• Dec. 28 6.90%
• Dec. 14 6.86%
• Dec. 16 6.74%

By the way, you have to factor in these discounts when negotiating your price. Take prices available from Edmunds.com and KBB.com and then subtract 7% to come up with a price you are willing to pay. Trust me - dealers want to close the books on 2009 with sales.