Re: Please close the door of the car is this right
More natural to me would be
Please open [or close] the car door [or window].
There is nothing ungrammatical about your #1 - #4. I just wouldn't say them.
5 is fine.
6 - Don't use "key." (There is something called keying a car, but it's when you deliberately ruin the paint job of a car by running your keys along the side. It's an act of vandalism.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.