Kurt McNeil, GM's U.S. sales chief, said the fundamentals are still in place for GM and the industry to rebound in the coming months. Jobless claims are falling, home prices continue to recover, gas prices are down, household wealth is rising and the Federal Reserve has postponed the end of a bond-buying program that kept interest rates low, he said.
"As long as the underlying economic factors are supporting the business, which we believe they will through the end of this year and into 2014, we'll get through this turbulence," said Ken Czubay, Ford's U.S. sales manager.
Jim Lentz, Toyota's North American CEO, told The Associated Press in an interview that people have grown used to dysfunction in Washington.
Earlier this year, when the government failed to avoid automatic spending cuts known as sequestration, there were predictions that the economy would melt down, Lentz said.
"Basically they were told that when you wake up tomorrow, the Earth is going to stop spinning," Lentz said. "For the most part the Earth didn't stop. And I think that's how they view this again."
The shutdown will only affect sales if it causes credit markets to tighten, Lentz said. That will be a problem, he said, because low interest rates and abundant credit have helped fuel the auto sales recovery.
There was concern among executives and analysts that a long shutdown and a looming confrontation over raising the government's debt ceiling could eventually cause sales to fall. McNeil said anything over two weeks could cut into consumer confidence.
"Consumers don't like to make big-ticket item purchases when there's a lot of uncertainty in the economy," said Jesse Toprak, senior analyst for the TrueCar.com auto pricing site.
One reason GM's sales fell last month was a reversal in pickup trucks, which have been hot-sellers. Sales of GM's full-sized pickups, the Chevrolet Silverado and GMC Sierra, fell 8 percent even though the company is selling redesigned trucks.
Some versions of the trucks were slow to reach showrooms. At the same time, Ford's F-Series pickup, the top-selling vehicle in the nation, posted nearly a 10 percent increase, and sales of Chrysler's Ram truck rose 8 percent.
Ford and Chrysler offered more than $4,000 in discounts as they sold down 2013 models, according to the Edmunds.com auto site. But GM reduced its incentive spending almost 30 percent compared with last year to about $3,900.
While touting its incentive discipline in September, GM announced increased discounts starting Tuesday, including $1,000 cash on a 2014 Silverdo and up to $4,500 on a 2013 model.
Pickup trucks are traditionally the top-selling vehicles in the U.S., and they're key to automakers' profits. Companies make around $10,000 per truck.
McNeil said GM's sales should return to normal levels for the rest of the year. Through September, the company's sales are up almost 8 percent from a year ago.
At Honda, sales dropped 10 percent as two of its most popular models, the Accord midsize car and the CR-V small crossover SUV, posted declines. Sales of the Accord, which have been hot all year, fell nearly 14 percent, while CR-V sales were off almost 4 percent.
Other automakers reporting sales included:
Ford Motor Co., which bucked the industry trend with a 6 percent sales increase. Ford was led by sales of its Fusion midsize sedan, which jumped 62 percent over last September. The subcompact Fiesta posted nearly a 29 percent gain. But sales of the Escape SUV one of Ford's best sellers dropped 2 percent, and Explorer SUV sales were up just 1.5 percent.
Chrysler Group LLC, with a 1 percent increase aided by the Ram and the ever-popular Jeep Grand Cherokee with sales up 19 percent.
Toyota Motor Corp., which posted a 4 percent sales drop. Sales of the midsize Camry, the top-selling car in the U.S., fell 7 percent, but the redesigned Corolla compact posted a 1 percent increase.
Nissan Motor Co. reported a sales drop of nearly 6 percent. The company's top-selling Altima midsize car, posted a 13 percent sales decline.
Volkswagen AG, which has struggled all year against strong 2012 numbers, had a poor month. Its top-seller, the Jetta small car, posted a nearly 10 percent sales decline.
Hyundai Motor Co., which also has struggled this year, posted an 8 percent decline. Sales of its Sonata midsize car were down 20 percent.
