Automakers, already poised to break U.S. sales records for both November and the year in a strengthening economy, are leaving nothing to chance: They're boosting rebates and other deals in an effort to swipe market share from rivals. Aided by offers ranging from zero-percent financing and rebates to Ford's Friends & Neighbors discounts, the carmakers spent 6 percent more this month on incentives than they did a year ago, according to TrueCar Inc., a vehicle pricing research firm.