Used vehicles saw the biggest monthly declines since the pandemic boom, while new cars are about to plummet in value due to an oversupply crisis that is shaking the US auto market.

Still, higher interest rates are making monthly car payments far more expensive than they were just a year ago, and many Americans who bought a vehicle in the past couple of years, and are now seeing its cost fall off a cliff, are already underwater on their loans, which indicates that a wave of financial turmoil is right ahead.

From May to June, wholesale used vehicle prices declined by a record 4.2 percent, according to Manheim Market Insights. More notably, the Manheim Used Vehicle Value Index, a closely watched measure of prices, plunged 10.3 percent year-over-year in June. Compared to one year ago, prices for pickups and vans went down by 6.6 percent and 8.5 percent, respectively. Sports cars were the worst off, falling 14.8 percent in prices compared to last year, while compact cars and midsize cars each dropped by more than 12 percent from June 2022.

Looking ahead, the three strongest predictors of used car prices – new vehicle inventories, new vehicle incentives, and the new-versus-used price differential – all point to a significant crash, the firm notes. In fact, Goldman Sachs analysts lowered their user car inflation forecast by 4 percent to -11 percent, which means that the bank is assuming that used car prices are going to face a 14 percent downside from current levels by the end of the third quarter. That would result in an almost 25 percent crash in a span of just six months, and an oversupply crisis in the new car market could bring the price of used cars even lower before the end of the year.

Right now, the market for new cars is in a strange state. UBS analysts argue that a price war is on the horizon with dealers duking it out by dropping new car prices. In May, new-vehicle inventory reached its highest level in two years, with a notable increase from the previous month. Charlie Chesbrough, Cox Automotive's senior economist. says that the new car market will continue to see weakening demand due to worsening economic indicators, and the increase in supply will force many dealerships and automakers to start offering discounts.