Answer: Joan will win.
Explanation: Even though Ace was following all safety precautions and driving rules, The damage inflicted on Joan's vehicle was during the course of Ace's personal use whichch is largely unauthorized. Had it been that Ace sought permission from Joan before embarking in the journey, his defenceman could probably have been more tenable so far he was keeping to safety precautions. However, the use of Joan's car without express permission from the owner could probably lead to Ace being guilty and Joan will probably win.