In October, used-vehicle sales saw a 3.5% decline year-over-year, with a total of three million units sold, according to Cox Automotive estimates.

There was also a decrease in retail used-vehicle sales compared to September due to one fewer selling day in the month.

Registration data suggests used-vehicle sales in October were slower compared to last year. The seasonally adjusted annual rate, or SAAR, is projected to have ended at 36.5 million, lower than last October's pace of 37.8 million but higher than September's revised level of 35.8 million, Cox said.

The decline wasn't expected, “given the affordability issues in the new market,” said Chris Frey, senior manager of Economic and Industry Insights at Cox Automotive. “Despite facing higher interest rates, the used market has remained strong, a result of the lower prices of used vehicles and the continued need for transportation among consumers.”

The volume of retail used-vehicle sales via dealerships in October is estimated at 1.57 million, just 0.4% lower than September's 1.58 million. In fact, the data showed October's retail sales pace rose to 19.3 million from September's revised 18.9 million.

The retail estimates for used-vehicle sales, which rely on registration data, generally correspond to estimates based on observed changes in advertised units tracked by vAuto, a Cox Automotive company specializing in inventory management. However, vAuto estimates show a 2% decrease in used retail vehicle sales volume from September to October.