No, "Her brother's car" is not a sentence, it is a noun phrase; it has no verb. For example:
Her brother's car is new. (the noun phrase is the subject of the verb 'is')
She's driving her brother's car. (the noun phrase is the direct object of the verb 'driving')
yes but this is a suggestion: The brothers are playing with fire crackers in the playground. It is correct yes
Yes, the sentence "Yesterday Tom washed the car" is grammatically correct.
Yes, perfectly correct.
They are Anu's brothers in law.
Remove 'it' word ... My car is beautiful
Yes!
To correct the unclear reference, you must reword the sentence. The sentence isn't clear that the pronoun 'it' refers to the suit or the car. Reworded: Take the suit to be cleaned when you take out the car. Put the suit in the car and take the car to be cleaned.
customers are going to purchase a car
Yes "She had a car" is correct in the sense that She used to have a car before but it is not there right now. It would be incorrect to the sense that She had a meal which means she ate the meal..
Past-tense. Solid wording.
Yes, very correct.
they're both correct depending on if your talking in past tense or present