the first man to buy a car, Robert Allison, a mechanical engineer of Port Carbon, Pennsylvania. Here's the account of the event, from Winton

We did not know where our customers would come from, but we were sure they would come. We started building four machines, and when one was finished, Robert Allison, hearing that I was manufacturing automobiles, came to Cleveland.

He wanted a ride. I told him to hop in, and then proceeded to give the first of many millions of demonstrations that since have preceded the sale of automobiles. 

We started out about noon and did not return until after supper. During the afternoon he had me drive to a dozen places where friends of his were working, and from each he sought advice. 

After each stop he had a new set of questions, but apparently I answered them satisfactorily, for when we returned to the factory he asked: “How much do you want for this carriage?”

“One thousand dollars.”

“I’ll buy it.”

Within a short time we sold the other three machines, getting $1,000 apiece. Our profit on each was $400.

The exact date of the sale was March 24, 1898, and about a week later — on April 1, 1898 — payment was received and the car was shipped

Winton bought it back after Allison had used it a few years, and it is now in the Smithsonian Institution

https://www.saturdayeveningpost.com/sep-keyword/winton-motor-carriage-company/

Believe it or not, I think I'm related to Robert Allison. I'll have to dig into the family tree project to find out