Car and truck inventories rose in May for the sixth straight month to 3,356,700 units on June 1, up 121,000 vehicles from one month earlier.
Since Jan. 1, the supply has increased by 398,800 cars and trucks.
Measured by days' supply, most automakers began June with lower inventories.
The Toyota Division of Toyota Motor Sales U.S.A. Inc. reported a 31-day supply on June 1, down from 38 days one month earlier.
Dodge had a 59-day supply of trucks, down from 64 on May 1, after a surge in truck demand gave the division as a whole a sales gain of more than 5 percent in May.
General Motors posted a 69-day supply on June 1, up from 62 days on May 1.
GM has been attempting to beef up inventories in recent months since concluding that some portions of its inventories were too lean to support sales demand. Retailers have asked the factory for more Chevrolet Impalas, large trucks and sport-utilities.
GM's May sales were off by 12.1 percent from May 2001 levels.
The industry's current inventory issues are to a certain extent still colored by the fallout of last September's economic pains. At that time, several automakers lowered production and sales expectations for 2002 and still are rebuilding their numbers.