DETROIT — U.S. auto sales grew at the fastest pace in eight years in June, surprising the industry and setting it up for a strong second half of the year.

Sales rose 1.2 percent over last June to 1.4 million cars and trucks, according to Autodata Corp. GM, Toyota, Hyundai and Nissan all saw increases over last June. Honda sales were flat, while sales at Ford and Volkswagen were down.

June’s annualized sales rate – which estimates annual sales if they stayed at the same pace every month – was 16.98 million. That was the fastest pace since July 2006 and higher even than May, which also surprised the industry with its strength.

May sales were helped by five sunny weekends and the Memorial Day holiday, which got June off to a slow start. But Ford’s U.S. sales chief John Felice said sales picked up at the end of last month as automakers started promoting Independence Day sales.

TrueCar estimated incentive spending rose 1.6 percent in June to an average of $2,735 per vehicle. Both GM and Nissan lowered incentives by 12 percent from last June.

While incentives may be lower, buyers are taking advantage of good lease offers and low interest rates. The average interest rate for a 60-month new car loan is 3.18 percent. Three years ago, that was closer to 5.5 percent, according to Bankrate.com.

GM’s sales were up 1 percent over last June despite a continuing parade of recalls. GM’s total safety recalls for the year reached 29 million vehicles on Monday, when the automaker announced six new recalls of 8.4 million cars. Two of those recalls were for ignition switch problems, the same issue that began the company’s recall crisis in February.