NOTE 1: I think you should be writing to the company that you hired the car from. So you are talking about "your car", not "our car".

NOTE 2: "Hopefully you will cope with the situation intelligently." - this is really rude! It sounds like you are calling them stupid :)

Dear Sir,

I am writing to inform you of an accident that occured when I hired a car (Toyota, Model: 2014, NO: PK111) from you for a one day trip with my family on Saturday.

Unfortunately when we were coming back from a hilly area an accident occurred due to the negligence of other driver. Suddenly he turned his car to the right side without using his indicator. I tried my best to save myself but I hit the back of his vehicle, which caused damage to our car's headlight and his back light.
Immediately after the accident I called the police, who arrived in under five minutes, and wrote their report about the incident. The police told me that they will call you if required.

I am sending you the pictures of your car along with a copy of the police report.

Please let me know if you need any further information.

IELTS Writing Task 1 Practice Letter No 8, Correct it Please

You should spend about 20 minutes on this task.
Your car is hired from a company and while you are driving on holiday, you have a small accident. You will have to write a report to the company to explain it.
In your letter:
• when and where you hired it
• describe how the accident happened
• what kind of action did you take after the accident
You should write at least 150 words.

You do NOT need to write your own address. Begin your letter as follows:

Dear Sir,

I am writing to inform you that on Saturday I hired a company’s car (Toyota, Model: 2014, NO: PK111) from our regional manager of north region for the one day trip with family.
Unfortunately when we were coming back from the hilly area our accident was occurred due to the negligence of other driver, suddenly he turned his car to the right side without giving any indicator, I tried my best to safe myself but it I hit on the back of his which caused the damages of our cars headlight and his back light.
Immediately after accident I call the police who arrived in nearly five minutes, police writes their report about the incident. Police told me that we would call you if required.
Moreover I am sending you the pictures of our company’s car along with the copy of Police report for necessary action.
Hopefully you will cope with the situation intelligently.

Regards
Awais