The thing with Seinfeld is he is a terrible person, and he knows this. In fact, he makes no bones about it. That's the point of the show Seinfeld. That was the point of the finale. All of the people whom they had transgressed over 9 years come forth and say how very, very bad Jerry and his friends are. In the end, Jerry and George have the same conversation as the first episode. It all comes full circle. There is no character arc or development. They stay horrible.
What's great about Comedians in Cars is he talks with other comedians and writers about the craft of comedy. You can tell it's something he's deeply interested in. It's like he's interested in the theory and execution of comedy. I think he also gave standup a bit more credibility than it may have had previously. He intentionally refrained from using a lot of bad language and crude jokes (as noted in the HBO special) because he wanted the jokes and humor to stand on its own. It's like a good steak. A good steak shouldn't require a bunch of bullshit. If you need A1, then it's not a good steak.