Based on articles here, here, and here, some diners were converted streetcars, but most were prefabricated in a factory and shipped to their location. The shape was dictated by what would fit on a railcar or truck.

How the heck they double decked a coney hotdog?! Gosh I really want one now, too!

In addition to Best Ice Cream and Good Coffee, the breakfast had So-So Scrambled Eggs.

Being an apostrophe fan, I note the ice cream logo in the ad says "Best's Creamy Ice Cream" but text in the ad says only "Best Ice Cream." I suspect the loss of the apostrophe happened organically over time, as people just called the stuff Best. We didn't have Best in the Midwest (although, hey, it rhymes) so I'm unfamiliar with whether it was truly the Best.

So cool, I wonder how common it was to repurpose old street trolleys as diners.

For Notcom, the older folks here in Rhode Island sometimes refer to hamburgers as hamburgs. My mom did - "We're having hamburgs for supper!" Perhaps they did that in New York, too?

There is a 4th North Street which would have been near, but not in Syracuse in 1941. It's a short stretch, x to x on the attached map. A diner might be successful there because 4th Street intersects U. S. Highway 11, north of Syracuse.

I'm sure John Collier cropped the diner on the left to not show an addition built for the kitchen, storage, restrooms, etc. The charm here is in the former streetcar. Someone went to the trouble of building a brick skirt and steps, and planting shrubbery. I wonder how long they operated.

Thirty years old, at that point, to be exact

Hamburg, in addition to being a stadt in Germany, is also a town outside Buffalo ... I'm not 100% certain someone who ordered one would end up with what was expected. (Then again if they don't seem to be "good" or "regular" they aren't called "surprising" either).