Our driver, Mr Smith, said the driver of THE car hit our truck from behind and broke said driver's mirror.
Is this homework????
You need a comma after Smith, and a the in front car (of car? what car?)
There is no comma after behind because " and broke said driver's mirror" is not a complete sentence. You can't just say "Broke said driver's mirror" There has to be someone or something to break it--if it's a complete sentence.
There is also something wrong with "Mr" but I'll let you figure that one out ;)
The more I think about this, the harder it is. Grrr.
It could be:
Our driver, Mr. Smith, said, "The driver of THE car hit our truck from behind and broke said driver's mirror."
I can see how 'said' works because we don't know the sex of the driver.