Backlink still have great value for auto repair website SEO. However the type of link and degree of separation affects the SEO value of the link.
Search engines base a high portion of the search rating they award a website on the number and quality of links linking to a website.
A two-way or reciprocal link is where website “A” links to website “B” and “B” links back to “A”. Basically a "you help me and I'll help you" arrangement. Since these type of links are typically between companies who know each other they have a lower value than a one-way link from a stranger.
Rather than two websites linking directly to each other a one-way link from an unrelated website has a high value.
One-way links are much more difficult to get and so they are awarded a much higher search engine ranking value. The reasoning is that since one-way links are so much more work to attract the majority should be authentic backlinks.
Many website owners will buy backlinks to their websites to boost their website ranking. But this is very risky practice. If the website you purchase a link from is found to be selling links and banned or black-listed by the search engines your website will be found guilty due to your association to them. Recently Google has been on a very aggressive campaign to find and punish websites that break their terms of service ban on paid back-links.