No, for two reasons:
First, Bitcoins are very divisible. So it wouldn't create the kinds of problems having a penny be enough to buy a car would create. (How would you buy a candy bar?)
Second, while deflation would provide an incentive for people to hoard a currency rather than spend it, it provides an equal incentive for people to try to pry that currency out of other people's hands by any means. If I'd rather hold my Bitcoins than spend them (so that you'd have to offer me more for them), you'd rather have my Bitcoins than something else (so you'd be willing to offer me more for them). It simply cancels out.