I'm a stupid man.

One hour ago, I drove a car of a company and went to a convenience store. I bought a lunch box and Japanese tea for lunch. When I returned to the car, a uncle man/guy who I didn't know sat down at the passenger seat of the car. We were looking at each other reciprocally for about 10 seconds and then he said: "Why do you sit down on my car selfishly?" I got out of the car though I think it's somewhat strange (weird). I saw a car with the same color and type as mine. It's the 3rd time that I took the wrong car.

I'm a stupid man.

One hour ago, I drove a car of a company (Was it the company you work for? If so it should be "my company car, if it was a rental company then you can say "a rental car") and went to a convenience store. I bought a box lunch and Japanese tea for lunch. When I had returned to a the car, the uncle a man , who doesn't  I didn't (doesn't is used for describing someone else's view in present tense. Past tense you would use didn't or did) know, was sitting in the a passenger seat of a car. sat down. I was looking each other reciprocally We looked at eachother (Using we makes it known to the reader that both people did the same action. So you wouldn't use "reciprocally" for this circumstance) for about 10 seconds And an uncle said. (This you can either say "when the man said or take out the period and insert "before the man said, "Why do you sit down on my car?" selfishly?  (Is the man calling you selfish? or was he being selfish? In English we wouldn't use this word in this way.) I have gone got out from a the car though I thinking it's somewhat strange. I saw a the car with was the same color as the same car type equaling  and same make as my car. It's the 3rd time that I took the wrong car.

Sorry for the red. でもあなたの物語は面白いと思いました。