A recent study from R.L. Polk, which tracks the auto industry, finds Americans are holding on to their cars longer because we are nervous about the overall economy.

Noting that The Conference Board finds consumer confidence at an all time low, Polk said it found Americans are putting off the purchase of a new vehicle and spending money servicing their existing ones instead.

No surprise there, I suppose. As Polk points out, many consumers put off buying a new vehicle in 2008, "judging by the fact that light vehicle sales in 2007 dropped from 16.1 million units to 13.2 million in 2008." And sales this year are widely expected to be around 10 million units.

But Polk was able to put some numbers on the trend.

"One telling sign of tough times is that consumers are maintaining their vehicles longer than in the past, according to vehicle retention trends," it said in its report.

It said it found the "average length of time that owners held onto a new car or truck in 2008 was more than four and a half years (56.3 months)" compared with just over four years (49.4 months) in 2002.

"Our study supports a continuation of this trend," Polk said. "Almost two-thirds of consumers said they were 'extremely or very likely' to keep their vehicles longer than they might otherwise."

"An additional 25 percent of respondents were 'somewhat likely' to keep their vehicles longer, meaning that only 11 percent projected that the length of ownership of their vehicles wouldn't be impacted by current economic conditions."

And it said that of the Americans still buying vehicles, "seventy percent stated that they were at least 'somewhat likely' to consider a used, rather than a new vehicle for their next automotive purchase."

It said this finding was supported by "reports of rising used vehicle prices."

- Peter C. T. Elsworth