There's always the usual: How fast will it go? What kind of mileage do you get? etc.
The best comment I have frequently heard at gas stations is, "What year is that car and what color is that paint?" Once I tell them it's a Kewanee Green 1930 Model A Ford Tudor Sedan, they say, "Yeah, my granddad had one exactly like this except it was a red 1950 Buick station wagon . . . just like yours!"
I stopped for a cup of coffee one Saturday morning at McDonalds and a lady walked up to me as I was getting out of the Model A and asked, "How old is that car?" I replied, "Eighty-three" and she yelled at her husband, "Delbert! Get the camera, this car was built in 1883!"
On that same stop at Mickey D's, when I came out of the restaurant I discovered that the car wouldn't start so I opened the hood to check the fuse; a man walks up and starts talking to me while looking over my shoulder into the engine compartment and complimented me on the restoration and then remarked, "Did you do the work on this car yourself?" I replied, yes and he said, "You can sure smell that fresh paint!" I just smiled knowing that I had painted the car in 1972 (41 years ago).
Last comment - why is it so many people (particularly teenagers) seem to always ask, "What's it worth?" or "What'd you have to pay for that thing?" I have tried to be diplomatic and not shoot back with, "That's sorta personal, what did you have to pay for that pair of shoes?" Rather thought it was best just tell them, "I paid $750 for it." I then pause and add . . . "41 years ago."