The grammatically correct way would be: To whom did you sell your old car?
"why don't you?" is a question. "why you don't" is a command. Why you don't? is not a correct question. Also it is not a command. Why can be used to give a suggestion or piece of advice eg. 'Why don't you sell your car by advertising it in the paper?' I think 'why you don't' is a variation on this usage eg 'Why you don't sell that car I'll never know'
Yes. "The car that just passed was theirs" is grammatically correct.
Yes, very correct.
All three sentences are grammatically correct. Each one follows the standard subject-verb-object structure and uses appropriate punctuation.
The sentence "He gets farts in the car" should be written like this. "He gets in the car and farts" or "He farts in the car
Verb
"to sell" would be correct. You sell your car and made a sale.:)
Only if you are car surfing (riding on the top of a car with your hair whipping in the wind as it is speeding down the road). The more commonly used sentence would be "I'm in the car" which means you are sitting in the car.
Grammatically, 'quiet' should be 'quietly', which is an adverb. The adjectives are old and new.
I did not sell my car, I still have it. You do realize your question makes absolutely no sense?
yes....you can sell one with out the windshield if you wanted.....The question should be would some one buy a car with a chipped windshield!
The question as asked is grammatically incorrect. It requires a verb and an article or changing the object to a plural.Such as these examples:My brother is skilled at fixing a car. (which is a little awkward)orMy brother is skilled at fixing cars.