My son does not like to do his school work, he does not have a problem going to school but only because he gets to play a lot with his school friends. I dont know what to do with him sometimes I feel like he is immature for his age. He still cant wirte or read english words properly. Is he not old to be playing with the cars (pushing him)

I think that childhood is very short these days. Don't stop your son playing if he needs to do that. There is nothing wrong with playing with cars at 9.
I thin many, many boys are like your son, not wanting to work and write.... however, it is a fact of life that they have to learn.
If you are worried about your son's progress at school, I would speak to his teacher. Ask her/him how you can support your son and how he is progressing at school. If he needs extra help, ask her if he is getting it and ho you can help.
Don't worry if he is immature, he will grow up in time. At 9, he is still young. Speak to his teacher. If he needs to do work at home.... maybe develop a system where he does 15 mins and then plays for 30 mins... Maybe you could turn the work into a game?

Sounds like school is not good for him. I like to follow the child's lead. The "program" is in his brain. If we push them to read before their eyes are ready they end up with glasses and anxiety about reading. Have you considered home schooling or a different, more progressive school that will honor his time table?