There is a federal law that basically says that if someone sells you something at your front door then you probably have the right to cancel the deal within 3 days. Other than that, there generally is no legal right to cancel sale. Since car dealers generally are not allowed to sell cars unless the sale is taking place on their lot, the federal 3 day right to cancel law is not likely to cover you. However, there are other laws that strictly control what car dealers can and can not do when selling cars to people and a violation of those laws may give you the right to cancel the deal. To find out for certain, you need to talk to a Consumer Law attorney. Contact your local attorney Bar Association and ask for a referral to a Consumer Law attorney or look for a local attorney on this National List of Consumer Law Attorneys here: http://www.ohiolemonlaw.com/ocll-site/ocll-locate_local.shtml
does NOT list Kentucky attorneys, so it is unlikely that you will find an attorney on this site to answer your question.
There are a few attorneys that are in other states that are also licensed in Kentucky, but they seem few and far between. Do the following search on Google to find those lawyers:
site:attorneyqna.com kentucky bar