The number of used vehicles sold in the U.S. in 2021 hit an all-time record, according to Cox Automotive, bolstered by a robust spring selling season that analysts say may not be easily repeated.

Cox Automotive, which has more than 40,000 auto dealer clients across five continents, estimated that overall used-vehicle sales for 2021 were 40.9 million, an increase of about 10 percent compared with 2020. 

Of those, an estimated 22.2 million were retail sales — vehicles sold to consumers by dealerships and other retailers such as Carvana. That also was an all-time record, Cox said, and reflected an increase of nearly 13 percent year over year.

But the records will likely stop there, at least for a while, according to Automotive News.

The used-car market will remain strong in spring 2022, but it will "struggle to see any change in volumes" compared with the record amounts last spring, Cox Automotive Chief Economist Jonathan Smoke, told Automotive News.

Cox Automotive analysts said they expected used volume to soften more in subsequent years as reduced new-vehicle production in 2020, 2021, and 2022 cuts down the number of vehicles available for the used market.

In New Zealand, the used vehicle market has also been strong, especially for 2020 vehicles due to the global supply issue. Anecdotally, AutoMuse has been heard for vehicles such as a 2020 Toyota RAV4 hybrid selling for the same price as a 2021 model.