Ray Magliozzi looks over an engine Thursday, Oct. 1, 2009, at his Good News Garage in Cambridge.

If Cambridge needed another tribute to the Good News Garage, the auto shop famous for its association with National Public Radio “Car Talk” hosts Tom and Ray Magliozzi, it’s here.

The short version: If you have a problem with your car, you should take it to the Good News Garage, at 75 Hamilton St., south of Central Square. The garage crew is tenacious and good-hearted and you will part with your cash — it’s a cash-only operation — gratefully and with relief.

The long version mainly ponders what is wrong with so many other auto shops.

As keepers of esoteric knowledge and saviors of the helpless, auto mechanics tend to have a lot of swagger.

Like others in this category, though — doctors, primarily, with scientists offering a few outstanding examples and priests being the historical mold that should have been broken — they have less right to brag than they like to think. Too many auto mechanics don’t really know what they’re doing. They hurt as much or more than they help by substituting hubris for experience and relying on customers being too ignorant to know the difference.

This is criminal because car problems usually lead to other, bigger problems, like the human body but unlike most modern technology.

If a laptop battery dies, you can work by plugging in to an electrical outlet. If the monitor is shattered, you simply can’t see what the computer is telling you. If the logic board is broken, the computer will turn on and the monitor will work, but you can’t really compute.

Break a rib, though, and it can puncture an organ and cause you to bleed internally. If you live and are recovering in the hospital, watch out for infection; your immune system is weakened, and you could die. And when a timing belt goes in a car’s zero-tolerance engine, the engine is a goner. Get a flat tire and drive too long or too fast on it, you might crack your rim and need a realignment. Drive on a cracked rim or a misaligned car and you’ll keep getting flat tires.

I bought my used car with confidence because I’d paid for an inspection at The Benz Den in Belmont and got a clean bill of health. I hadn’t been driving long before I discovered cruise control didn’t work, and workers at the shop confessed they’d forgotten to check it. I was angry, of course, and the shop agreed to fix the problem — leading to a months-long game of me bringing in the car when I could and the mechanics being unable to fix the problem because it mysteriously never occurred when they had possession of it. I suspect cruise control wasn’t the only problem missed by the mechanics, but knowing of that single thing would have been enough to make me change my mind about buying the car, the purpose of which was to take me on a daily two hours’ highway commute at odd hours.

And I had that timing belt problem and had to replace my zero-tolerance engine. Breault’s Auto in Rehoboth did the work, because I was working in Taunton at the time, and the owner was cheery and apparently thrifty. Those things seemed less important when a “check engine” warning light came on the instant I started the car with its brand-new used engine. The owner of the auto shop worked on it countless times, but the warning light wouldn’t go away. (Now that warning light is an automatic fail on the state inspection.) An Audi technician told me much later there were two engines for that year’s model, and Breault had installed the wrong one.

And much later than that an equally knowledgeable auto technician told me that the “wrong engine” diagnosis was nonsense.

I believed that technician, just as I believed the one who gave me the nonsense in the first place. How would I know? They’re the ones with the special Audi computers, and I’m the one helplessly coughing up $80 an hour to be lied to or guessed at.

Speaking of which, it was an Audi dealer that charged me $80 to find out my own radio-restart code when my battery died, engaging its anti-theft shutdown feature. I hadn’t known there was such a thing when I bought the car, so I hadn’t known to ensure the seller include it in the sale. (And he hadn’t.)

Eighty dollars for the code to my own radio, in my own car? That Audi dealership made its $80 and never a penny more from me, despite my earlier vow to use dealers for all repairs and maintenance so I could keep the car running smoothly forever.

In that way, too — meaning charging in ways that scare off even customers seeking preventive care or badly needed repairs — auto mechanics can be like doctors.

The Good News Garage, though, is like the best of doctors, who genuinely care about patients and outcomes, and who pursue a problem as an expression of their passion and ingenuity. Like the best of doctors, engineers and other keepers of hands-on if sometimes esoteric knowledge, the Good News Garage mechanics are problem solvers, and their problem is the one you bring them, not how most easily to get you to pay and get out.