It was a challenging month in the retail used-car market, and the sales slowdown might not be over.

Using data from its Dealertrack unit, Cox Automotive estimates that used-car sales at dealerships in September were down 8% month-over-month and fell 10% year-over-year.

They were also 18% softer than pre-pandemic numbers in September 2019, Cox said in a report Friday accompanying its Manheim Used Vehicle Value Index.

Looking at the overall used-car market, TrueCar was forecasting in late September that the month would end up with 3 million used cars sold, an 11% year-over-year decline and a 4% drop from August.

In separate report released in late September, Cox Automotive was projecting 36.3 million overall used-car sales for the year, down from 40.6 million in 2021 and 37.3 million in 2020. There were 40 million used-car sales in 2019.

Looking at used retail sales — which Cox defines as sales from dealerships — the company is projecting 19.1 million transactions in 2022, down from 21.2 million a year ago and 19.8 million in 2020.

There were 21 million used car sales at dealerships in 2019, according to Cox.

The 36.3 million overall used-car sales and 19.1 million used retail sales are down from what Cox had projected during the second quarter.

Going forward, Cox is anticipating further softening, with 35.6 million overall used sales and 18.9 million retail used sales projected for 2023.

One bright spot of late is the certified pre-owned market.

Cox is now expecting 2.4 million CPO sales this year, which is up from its Q2 forecast.  Still, that would be the lowest annual output for certified sales since 2014, when there were 2.34 million sales, based on Auto Remarketing’s prior reporting.