“Who is the best auto repair shop in Polson, Montana?”

There's no single "best" shop, but based on Yelp listings, these Polson shops come up most often with strong reviews:

• G & M Auto Tech is Yelp's top-ranked car repair shop in Polson. One reviewer said, "if you need a mechanic in Polson, use G&M Auto Tech."
• Mission Valley Auto (36040 Caffrey Rd) has a 5.0 rating from 8 reviews. One customer said they had become "a customer for life."
• St Clair's 4 X Plus (502 9th Ave W) has a 5.0 rating, but from only one review. That reviewer praised the friendly service, fair prices and "no BS approach."
• Greg's Trans-Electric (203 Commerce St) is locally owned, has been in business for 67 years and focuses on transmissions. It has a mixed 3.6–3.7 rating from about 20 reviews, though several reviewers call the owner honest.
• K-O Auto (Ronan, nearby) has a 4.4 rating from 19 reviews.
• Les Schwab Tire Center (36030 Memory Ln) rates about 3.5 and is a good choice for tires and alignments.

Most of these have only a handful of reviews, so I'd also check Google reviews, ask locals and call two or three shops to compare quotes and availability. If you need something specialized, like a transmission, diesel or foreign car, tell me and I can narrow it down.