Despite hundreds of thousands of lost units of production from a global semiconductor shortage, U.S. auto retail sales are expected to reach record highs for April, but only time will tell when depressed inventories will disrupt those volumes.

The forecast is the latest from market research firms J.D. Power and LMC Automotive. The report says the continuing demand has lessened the need for incentives and increased transaction prices and profits, demonstrating consumers’ willingness to pay more and to buy pricier vehicles. The April forecast represents a seasonally adjusted annual rate of 18.1 million U.S. sales — more than the peak 17.5 million vehicles sold in 2016.

Stellantis NV on Wednesday said it was extending downtime at its Windsor Assembly Plant in Ontario, where it makes Chrysler minivans, for the first week of May. The Jeep Cherokee and Compass plants in Belvidere, Illinois, and Toluca, Mexico, also will idle.

“With the sales pace exceeding the rate at which vehicles are being produced, compounded by significant production disruption due to the microchip shortages, there is a growing risk to the industry’s ability to sustain the current sales pace in the coming months,” Thomas King, president of the data and analytics division at J.D. Power, said in a statement.

Relief isn’t expected until the second half of the year. Stellantis NV on Wednesday said it is extending downtime at three North American plants due to the global semiconductor shortage. Belvidere Assembly Plant in Illinois making Jeep Cherokee SUVs, Windsor Assembly Plant in Ontario making Chrysler minivans and Toluca Assembly Plant in Mexico making Jeep Compass SUVs will be down through the first week of May.