Automakers started October with larger-than-normal vehicle stocks after U.S. light-vehicle sales fell 0.7 percent in September.
Industrywide inventory stood at 3.7 million vehicles as of Oct. 1. That was up more than 111,000 vehicles from Sept. 1 and 234,000 from the beginning of October 2015.
Based on September's sales pace, companies had an average 64-day supply at their disposal, higher than the average of the previous five years on Oct. 1.
Nine automakers' days supply grew during September from the month earlier, while five companies' days supply shrank.
Mitsubishi Motors had more supply than any rival. Its 127-day supply was unchanged from August.
Toyota Motor Sales U.S.A. and Volvo Car had the largest gains, both growing by eight days. American Honda and Jaguar Land Rover followed with gains of seven days.
Volkswagen Group had the largest decline in stock, falling by six days to 61 days.
Subaru of America gained two days of supply to 23 days, though it remained the automaker with the smallest stock, by 20 days.
Following Mitsubishi, Ford was second among the automakers, with an 80-day supply. General Motors was third with 79 days, followed by Fiat Chrysler at 73 and Jaguar Land Rover at 66.
At 112 days, Fiat had the highest days supply of any brand besides Mitsubishi.
Lincoln had the third-largest stock at 101 days, followed by Buick at 89 days.