A spokesman claimed Vauxhall's new car pricing policy was beginning to have a positive knock-on effect on confidence in the used market.
“Vauxhall is not planning to drop new car list prices, which helps to keep used car residual values strong,” he said. “It gives the customer confidence to buy in the used market.”
Network Q sold just over 10,300 cars last month, up 2.5% on the 10,000 sales in August 1999.
Martin Brown, Network Q brand manager, said: “There has never been a better time to buy a used car, with values about £500 to £1,000 cheaper than in 1999, and a host of other incentives such as finance and insurance to help the consumer with the purchase.”
The spokesman said Vauxhall's internet strategy was also driving used car sales.
“We are selling more cars online, which helps Network Q to satisfy customer demand. The website has been busy,” he added.