US car sales rose strongly in September, with gloom over economic prospects offset by consumers’ need to replace old vehicles, easier credit conditions and an improved supply of Japanese vehicles.

According to preliminary data, light-vehicle sales climbed to slightly more than 13m units at a seasonally adjusted annual rate, from 12.1m in August and 11.8m in September 2010.

General Motors reported a 20 per cent jump in sales from a year earlier, and Ford Motor a 9 per cent increase. Chrysler posted a 27 per cent gain, reaching its highest September sales volumes in four years. Demand for sport-utility vehicles and pick-up trucks was especially robust.

Japanese carmakers were still trying last month to reach normal supply and inventory levels following disruptions caused by the March earthquake. Toyota’s sales were down 17.5 per cent, and Honda’s by 8 per cent. Nissan, which was less affected by the earthquake, reported a 25 per cent increase.

John Mendel, head of sales at American Honda, said the company’s US plants were now back to normal production. “Truckloads of new vehicles began arriving in the last week of September and shoppers can now feel more confident that they will find what they want,” he added. Toyota had a similar message.

Volkswagen boosted sales by more than a third, helped by new Passat and Beetle models.

Don Johnson, GM’s vice-president for North American sales operations, painted a mixed picture of consumers’ mood. “We’re concerned about confidence … and the budget battles in Washington”, he said. Even so, with the average age of existing vehicles now close to 11 years, “a lot of these people have to buy and come back into the market”.

Mr Johnson added that low interest rates, credit availability and high trade-in values had made cars “very affordable”.

Some carmakers have also pushed up discounts and other incentives in recent months, partly to run down inventories of 2011 models. Edmunds.com, an online car pricing service, said that Honda had been especially aggressive in a bid to win back market share after the earthquake-related disruptions.

GM continues to project full-year 2011 sales at the low end of its 13m-13.5m target. However, achieving that target would require sales of 13.6m-13.7m at an annual rate for the remaining three months of the year.