ANyone that says you cannot take a car to an inspecting mechanic prior to a sale being complete is hiding something. Period. Once he has your money in hand, it will be a challenge to get it back.
Find another car.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
It would be valid evidence but the question is will you be able to get your money. If the mechanic does not have much money and he does cheat you, it does not make a difference what the contract says, you will be out your money. If he will not let you take the car to be inspected, you are asking for trouble. That is a huge red flag.
The information provided should not be considered legal advice. I am not licensed to practice in any State other than SC. The results of your case will depend on the presentation of evidence, the law and other factors that may change depending on an in depth analysis of the facts of the case. Please see an attorney before making legal decisions.
Mr. Deasy is correct. The seller sounds sleazy. There are plenty of cars out there. Purchase one from a more reputable seller.
The information provided in this answer does not create an attorney-client relationship. If you are interested in his legal services, feel free to call Chris at (303) 409-7635 at his law office in the Denver Tech Center. All initial consultations are free of charge.