It's hard to describe the look that appeared on David Letterman's face when Jerry Seinfeld told him why he chose to make "Comedians In Cars Getting Coffee" a web-series: "I was thinking, what would be a good TV show for a phone?"

It was a mix of curiosity, thinly veiled confusion, and that look your dad would give you when you told him you wanted a tattoo.

Seinfeld sat down with Letterman after previewing the new season of "CCGC" at The Paley Center in New York City on Monday in an interview that felt more like a seminar on thinking outside the (television) box for the veteran late night talk show host.

After watching Jerry tool around Long Island in an old station wagon with Sarah Jessica Parker, Letterman's first few questions were variations on a single theme: "Why isn't this on TV?"

"Are you my agent?" Seinfeld quipped, after rejecting Letterman's suggestion that the series might be better suited for auto-centric TV network Velocity than the Internet. Letterman, who at one point asked what made the series “different than Funny Or Die," also wanted to know why the interviews on "CCGC" couldn't work in front of a live studio audience.

Seinfeld's theory was that, when attempting to show the meandering, silly and sometimes deep conversations that comedians share, you have to remove the audience to keep the participants from dropping into their acts.

"Being funny isn't what a great comedy act is about. Being funny is the fuel, but you have to have a machine to burn it, and that's the act," Seinfeld said, in one of several car analogies that he deployed throughout the night.

Letterman wanted to know why cars were such an important part of the show ("I thought you just found a way to write them off," he joked) and Seinfeld explained that it keeps people watching a show which is essentially (to coin a phrase) "about nothing" a lot longer than they might otherwise.

"Part of what makes the show watchable is that it's always moving. There's no narrative [to] drive the story. We know what happens. We know they're going to get coffee. You need a kinetic energy to move it along," Seinfeld said. "Moving people around keeps them awake."

There was another theme of the night: Letterman's genuine admiration for the show. He had done his homework; he even had favorite episodes — he recapped Louis C.K.'s boat story and called it "fascinating" — and described the Sarah Jessica Parker episode as both "delightful" and "lovely." The word "tremendous" was thrown around quite a bit as well.

When Seinfeld showed two pieces of raw footage followed by the edited versions, Letterman said he was "very impressed" by the finished product.

The audience was, too. Each episode of "CCGC" costs $100,000 on average (guests are paid, but Letterman refused pay for his episode) and it's safe to assume that a big chunk is used for the editing process. The episodes take just three-and-a-half hours to shoot. Seinfeld said that gives him "Just enough" raw material to create a 12-20 minute episode, but the contrast between the unedited footage and the finished product proved that skilled editing is even more important when your show has no plot.

With no writers or directors, Seinfeld sits in on the editing process, which takes a few weeks per episode, to make sure it all fits together. He has no boss or demands from producer Crackle, save for fulfilling his Acura product placement agreements, which he does with tongue-in-cheek, throw-away bits that almost make it tolerable.

After hearing about Seinfeld's lean production staff, lack of network meddling, and how an "edited talk show without an audience" can be watched on people's phones, Letterman seemed a little jealous of Seinfeld's web series, despite being a 30-year staple of American television himself.

""I'm envious of this," Letterman said. "I think this would almost be as satisfying as doing, 'Seinfeld.'"

"No, Dave," Seinfeld flatly said. "This is an hors d'oeuvre. This is a tapas bar. It's an anti-show about a nonevent. If you're being sincere, I'm flattered, but I don't know what you're talking about."

The fact of Letterman's impending departure from television also hung over the evening. He joked that, when people ask him what he'll do after retirement, he responds with, "Look for a job." He even suggested a spin-off series, "Comedians On Horseback Getting Coffee."

But, as a man who has spent 30 years idly chit-chatting with celebrities on TV, Letterman understood Seinfeld's love affair with talking shop with other comedians.

When asked what kind of person makes the best guest, Seinfeld said, "It doesn't matter, as long as I can engage with the person." However, they can't be "normal."

"Anybody who's normal, even a little normal, I'm lost," he said. "I'm not curious. I'm not interested. Oh, you've got a show? I don't care."

"You just described the last 30 years of my life," Letterman commiserated.