People who will go to a business, evaluate the business, then make suggestions on how to improve. Or even get involved and make things happen.
I am specifically looking for someone who would do this in the automotive repair industry.
How do I find someone who does this?
Have you ever used a service like this? How did it go?

Quality control, quality consultant. They probably call themselves all sorts of things. Many of these consultants hire mystery shoppers and mystery customers who then report back to the consultant they work for to help put together a competitive analysis.

If you are a sole proprietorship, not a chain, with just local customers, then you basically need a financial consultant more than anything specific to auto repair.
Or you might find a retired owner of a shop who was successful.

I know 3 men in various parts of the US or Canada who would be excellent, but I'm sure you can find someone close to you.

I have heard from different sources that auto repair gets tougher every year. Fewer bright kids go into it, and cars are more and more computerized, requiring workers with 2 sets of skills.

You need a pleasant looking place for customers, a pleasant place to work.
You need workers with good skills who have the incentive to stay with you, through raises and benefits.
You need a manager and office manager who can talk to customers about costs, and you need to know how to estimate while charging by the hour for most jobs.
You need a real bookkeeper.

Troubleshooter.

Business consultant.