Can a deal be reversed on a newly purchased vehicle?

My car broke down a week ago. I was told they could not find the reason it was not running. In desperation I traded it and signed a lease for a new car. This was yesterday. If I signed the lease papers, is it possible to reverse the deal now that I realize I just got myself into a debt outside of my budget. I feel I was forced into by the sales person. I only went in wanting info and came out with an 18,000 debt.