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The NPR series “Car Talk,” as anyone who listens to it regularly will tell you, was a little about cars and a lot about talk. Two brothers’ talk, in fact: Tom and Ray Magliozzi, the guys who hosted the show for 35 years, appeared to spend most of each episode trying to crack each other up while occasionally dispensing a few scraps of auto-repair advice from (as they described it) Car Talk Plaza. The brothers stopped producing new episodes in 2012, most likely because Tom — who died of complications from Alzheimer’s disease yesterday, at 77 — was in decline. The reruns, though, ran steadily after that, and I wouldn’t be surprised if they continue for awhile: The only thing that causes a “Car Talk” episode to sound dated is the occasional jarring moment when a caller asks for help with, say, a 1982 Peugeot. The hosts were and are the draw, not the stuff about fuel injectors.

Radio is an intimate medium, despite its facelessness — I suspect it’s because the microphone is very close to the host’s mouth, and thus, the voice in your headphones sounds close, like someone murmuring in your ear. Yet there wasn’t much murmuring on “Car Talk,” where a good 5 percent of the airtime was spent listening to Tom and Ray’s braying, rarely controlled cackling. They never would have made it on TV, where crispness and speed are the coin of the realm; in fact, in the 1990s, they tried a TV series, and it flopped. Even the car-obsessed Jay Leno, who had them on his Tonight Show, couldn’t turn Tom and Ray’s shtick into good TV; they kinda bombed there, too. On radio, their shambling style fit just right.

None of it would’ve worked at all, however, without a key element: Tom and Ray’s knowledge. There is a pleasure in watching (or listening to) people do whatever it is they’re really good at. Julia Child, the Project Runway people, Norm Abram: We take comfort in their expertise, particularly when it’s expertise we dramatically lack. At least someone knows how things are supposed to work. It’s the same jolt of pleasant surprise you get when you ask a friend about something related to her work, and abruptly see her step into professional drag and pull out a depth of knowledge you’ve never encountered before. You suddenly realize that she has an entire additional personality that her colleagues see but you rarely do. She has a small-scale, silo’d superhero identity.

That, I think, was their secret. Tom and Ray presented themselves as two guys yukking it up, but here and there, you’d see just enough brilliance peeking out around the edges that you knew something else was in their heads. Both were MIT graduates; both were engineers. They knew why a car works, not just how it works, and had the knack of explaining it, from first principles, with dopey-great analogies. They’re the sort of guys whom you’d like as your neighbors, particularly when a plumbing valve goes south on a Sunday. That ease with blue-collar aspects of life probably broadened their appeal: If you were a Republican, you could persuade yourself that they were in your camp. (Though I doubt they were, given that they grew up in Cambridge, Massachusetts, in the ‘60s and spent their entire careers in public radio.) Either way, they played cluelessness well, conveying only a sneaking suspicion of smarts. It’s no wonder that they once got a jokey call from the Space Shuttle, asking why it had such a loud rattle at 17,500 miles per hour. As it turns out, the cars did matter, nearly as much as the talk.

A certain number of comedy folks actively disliked the show. Tom and Ray weren’t ironists; their humor was apolitical, nerdy, broad, and blunt. They liked puns, and how-about-my-wife-ladies-and-gentlemen jokes. Comedic taste aside, it has also been argued that the sheer popularity of “Car Talk” pushed more substantive programming off the NPR schedule, paving the way for a bunch of silly game-shows. It’s a legitimate knock, if a stuffy one, and it essentially blames Tom and Ray for making something people really liked. For what it’s worth, the list of serious-minded radio people admired them is telling: Kurt Andersen, Susan Stamberg, and (with a few reservations) Ira Glass. There’s no shame in public radio’s having an entertainment arm, and Car Talk Plaza — joined with Garrison Keillor’s Fitzgerald Theater in St. Paul — remains its headquarters.