The US motor industry's traditional strong spring new car and truck selling season may be weaker this year, as analysts predict weak May sales despite another round of incentives, Reuters reported. With inventories already swollen and incentives running nearly 50% higher than a year ago, the news agency said, poor May sales could trigger more generous rebates and cut-rate loans while slow sales could also force steeper production cuts by Detroit's Big Three vehicle makers in the third quarter, putting a drag on any US economic recovery.