Resignation from the purchase contract, when is this possible?

Hello, I am not sure if the topic fits into this subforum, if not please move! I have already used the search function but in my case not received a suitable answer. Now to my request: I decided last Thursday for a car which I discovered online on mobile.de at a Ford dealer. After a short telephone call and clarification of the modalities I promised the seller to buy the car by phone. He then sent me an e-mail. rmular sent with the heading “Compulsory order of a used motor vehicle” . I filled it out, signed it and sent it back by e-mail. In addition, I transferred the total amount of the purchase price on the same day. In the order which the seller sent to me, it is stated in the appendix under the conditions: “The buyer is bound to the order for a maximum of 10 days. The purchase contract is concluded when the seller accepts the order of the purchased vehicle. The car should be delivered to me the next week, because I do not pick up the car myself. Since the vehicle is almost 500 km away. Before delivery the car dealership wanted to carry out a new TÜV and inspection. Since I found a clearly more attractive offer yesterday, I would like to ask if it is already too late to withdraw from the contract or which one. Costs would come to me. Would I be very happy about an answer! Greetings