Potentially you might have some sort of legal recourse against the manufacturer of the car for a design defect if the vehicle causes you distinct damages that you can establish in terms of dollars and cents as opposed to some general inconvenience.I would take the car back to the dealership to see what suggestions if any it may have to eliminate the discomfort that you are having with the vehicle such as back supports and the like.From what you have written, your back pain at this juncture that may be caused by the vehicle does not seem to warrant any legal recourse for you.