Here is a question I've asked several people. What would you do with extra money in your paycheck. Most who I ask say they would pay bills or save it. Does Obama expect a middle or lower class family to buy a new car with a tax break? I'll bet a rich person would. I'll bet a company would take advantage of the break to make upgrades too. That means that the middle class people that make the cars now get to keep their job or even get some overtime. I'm sure people barely paying bills would rather have overtime than a 20 dollar a week taxbreak.
Again, if everyone paid the same percentage it would be fair.