The Manheim Used Vehicle Value Index increased substantially again in March versus the same month last year.
Two things are driving the increase in wholesale, used-vehicle values at dealer-only auctions, according to Manheim parent Cox Automotive.
One is record-low used-car inventory. The other is income-tax refunds, said Cox Automotive chief economist Jeremy Robb, in a conference call April 7.
“We believe there’s still quite a bit of tailwind left in tax refund season,” Robb said in the call.
The Manheim Index for March was 215.3, an increase of 6.2% versus March 2025. The March index corresponds to a seasonally adjusted average price of $19,692.
That was the highest seasonally adjusted average price since May 2023. It was also the third month in a row of increasingly large increases in the index, compared with the same month a year ago. In the fourth quarter of 2025, the Manheim Index was roughly flat versus a year ago.
Robb said peak demand for used vehicles usually occurs during tax-refund season, when shoppers can use their tax refund for a down payment on a used car. The estimated average tax refund so far this tax season is $3,521, an increase of about 11.1% versus the same time a year ago, Robb said.
In addition, only about 52% of expected tax returns have been processed so far this year, against 58% at the same point in tax season last year, Robb said. “As we move to April 15, we expect to see more filing returns,” he said.
The Manheim Index is a single measure designed to track used-vehicle wholesale price changes, weighted for a changing mix of product segments and mileage, and seasonally adjusted. The index is calculated relative to a starting point, where January 1997 equals 100.
Besides bigger tax refunds, high new-vehicle prices are also driving some new-car intenders to switch to used vehicles, and that increases used-car demand, Cox Automotive said.
“Very tight” used-vehicle inventory also supports higher used-car prices, Robb said. According to Cox Automotive, new-vehicle retail inventory in March 2026 was just below 80 days, while used-vehicle inventory was only 37 days.
Days’ supply is an estimate of how long a given inventory would last before it’s sold out at the current monthly sales rate, and if the inventory were not replenished.
Robb said the current level of used-vehicle inventory is a record low for Cox Automotive, and the lowest since mid-2021.
