DETROIT -Zero percent interest loans and rebate offers may have been part of the Big 3 auto manufacturers' strategy to move more vehicles, but have consumers gotten used to too much of a good thing? A monthly study from Harris Interactive and Kelley Blue Book Marketing Research – AutoVIBES-indicated that as the frequency of manufacturer vehicle incentives rise, so has the car-buying public's dependency on them. The study reported that 50% of the U.S. adults in the market to purchase a car within the next year said they aren't likely to buy a new vehicle without an incentive, rebate or special financing. Almost 40% of those surveyed indicated they are heavily dependent on incentives. Representatives from Kelley Blue Book said auto manufacturers' incentives attract people who otherwise couldn't afford a new car to dealer lots to purchase one and put people upside down in their loans. Those buyers in turn become dependent on large rebates to help them recover from what they spent on their purchase.