New car sales have been in a downward spiral for over a year now, and the big beneficiaries appear to be used cars (and repair shops). A study by Manheim Consulting shows that the company's Used Vehicle Value Index has risen to a record high of 118.5 in the month of September, up 1.8% versus August. That's the ninth straight increase this year, as Manheim's index has steamrolled northward by 6.9% over the past 12 months.

New car sales have risen in part because many car buyers have decided to save money by buying used vehicles instead of new models, shrinking the supply of used vehicles on the market. And since fewer customers are buying new cars, dealers are left with fewer trade-ins. The month of September was especially impactful because many of the car-buyers who did buy new cars and trucks used Cash for Clunkers, and all of those vehicles ended up at the neighborhood crusher, not the used car lot.

Manheim's report also shows that both new and used vehicle inventories are down, which explains why new car incentives have been sliding as well. And with fewer incentives on new vehicles, used vehicles become a more attractive option, except there aren't many pre-owned units on the market. Used vehicles are going to auction with higher overall miles as well, a trend that is to be expected with the lack of vehicles coming off leases. According to Manheim, in January, the average auction car had about 51,000 miles on the odometer. That number has steadily increased over the past nine months to the point where an average auction vehicle now has closer to 63,000 miles on it.

With few used cars on the market and those models that are left tending to be of the higher mileage variety, it makes some sense that some automakers are becoming bolded in their volume projections for next year. Head over to Manheim Consulting for more info on its used vehicle index.

[Source: Manheim Consulting | Image: Justin Sullivan/Getty]