Edmunds, the leading car shopping and information platform, forecasts that 1,335,313 new cars and trucks will be sold in the U.S. in April for an estimated seasonally adjusted annual rate (SAAR) of 16.9 million. This reflects a 19 percent decrease in sales from March 2018 and a 6 percent decrease from April 2017. Analysts note that there were 24 selling days in April this year, compared to 26 last year.

"April's sales slip may seem disheartening, but the spike we saw in March was an anomaly considering our expectations for 2018," said Jessica Caldwell, Edmunds executive director of industry analysis. "Overall, we expect April will still be a solid month and more of a true indicator of where sales are trending for the year as demand declines and interest rates continue to rise. Sales are still in a very healthy place, and we're seeing encouraging signs that automakers are continuing to improve their product mixes and inventory levels to match consumer demand."

Edmunds estimates that retail SAAR will come in at 13.5 million vehicles in April 2018, with fleet transactions accounting for 20.1 percent of total sales. An estimated 3.5 million used vehicles will be sold in April 2018, for a SAAR of 39.2 million (compared to 3.7 million — or a SAAR of 39.2 million — in March).