Claims that August 2021 Consumer Price Index details proved used car prices started a downtrend ... appear to have been wrong based on the latest data

The Manheim U.S. Used Vehicle Value Index, a measure of wholesale used cars, increased 3.6% in the first 15 days of September compared with the same period last month, and is again back near all time highs. That's the first month-over-month rise in the index since May; in total the index has risen by more than 50% since the COVID lows in early 2020.