One way to track how well off-website ads work is to create an 'ad landing page' on your auto repair shop website.
Each 'ad' landing page must only be accessible from a link in an advertisement outside of your website. By counting the number of visits to the ad page provides a measure of well your ad is working and the leads generated by your advertisement.
Sure you could use a URL Shortener like Bitly to count website visits from the ad but people are often reluctant to click a link to a website that is different or unrelated to the company being advertised. By using a page on your website the link looks more legitimate and less risky.
Contact Us if you need help trying this simple ad tracking method.