U.S. Auto Sales Slumped in May

U.S. auto sales shifted downward in May as fewer selling days in the month led to less foot traffic in showrooms. 

Ford Motor reported a 6.1% decline overall to 234,748 light vehicles sold in the month, hurt by a 25% slide in car sales. Still, sales of F-series pickups rose 9%, and Ford vans hit their best tally since 1978, driven by Transit sales. 

General Motors said sales skidded 18% in the month to 240,450, as the No. 1 auto maker has dialed back sales to rental-car companies. Retail sales slipped 13%, mostly owing to the fewer selling days and "very tight supplies of new launched products," the company said. 

Fiat Chrysler Automobiles, meanwhile, reported its U.S. sales edged 1.1% higher in May as searing demand for Jeeps helped buoy results. The Italian-U.S. auto maker sold 204,452 vehicles in the month -- the best May sales level in 11 years -- compared with 202,227 a year ago. The Jeep brand logged a 14% jump to its best monthly sales ever. Meanwhile, sales in the Chrysler, Dodge and Fiat brands fell from a year ago and Ram remained flat. 

Sales were hurt by two fewer selling days in May compared with the same period in 2015. WardsAuto.com forecast a 6.5% industrywide sales decline based on a straight year-over-year comparison. Adjusting for the disparity in selling days, the firm expected the sales to increase 1.3%. 

Analysts had expected an annualized selling rate of 17.3 million vehicles in May, a modest slowdown in the selling rate compared with the same period in 2015 and flat with April. That rate, however, is higher than the rate set during the first four months of the year and likely adequate to keep the industry on pace for a second-consecutive annual volume record. 

Still, some prominent dealers have voiced concerns about underlying demand in the market after several years of market growth. Even as low interest rates and cheap gasoline boost the confidence of car buyers -- leading many to purchase pricier trucks or SUVs -- sales incentives and deliveries to fleet customers have risen amid weaker retail demand. 

The average price for a regular gallon of gasoline was $2.32 as of Tuesday, according to AAA, representing an 11-cent increase from a month earlier. Still, customers are paying the lowest price to fill up at this time of year since 2005, the travel organization said. 

Autodata estimated incentive spending had grown 14% through the first four months of the year. WardsAuto estimates dealer stock shrunk in May compared with April, but remains slightly above the end of May 2015. 

The average transaction price for a light vehicle sold in the U.S. rose 3.5% to $33,845, according to Kelley Blue Book, with Detroit auto makers logging the greatest gains on truck and utility-focused lineups. 

"Continuously growing demand for SUVs and trucks helped push overall average transaction prices up this month," said Kelley Blue Book analyst Tim Fleming, noting that the overall share of light trucks in May should show a rise to about 60% from 55% in the month last year. 

Write to Anne Steele at Anne.Steele@wsj.com