DOES YOUR HUSBAND SPEND TIME WITH YOUR SON, OR IS HE MORE OF A DISCIPLINE PERSON AND YOU ARE THE ONE WHO DOES MOST THINGS WITH YOUR SON?  IF THIS IS THE CASE, THEN I CAN UNDERSTAND WHY YOUR SON ACTS THE WAY HE DOES WITH YOUR HUSBAND.  HE MAY THINK IF HE GETS IN THE CAR BEFORE YOU DO, THEN YOU WON'T GO WITH THEM.  MY OLDEST DAUGHTER WAS LIKE THIS WHEN SHE WAS ABOUT 8YRS OLD.  HER DAD WAS USUALLY WORKING AND SHE WOULD ALWAYS ASK ME IF I WAS GOING TOO WHEN HER DAD WANTED HER TO GET IN THE CAR.  SHE JUST WASN'T USED TO SPENDING TIME WITH HIM WITHOUT ME AS I WAS ALWAYS HOME WITH HER WHILE HE WORKED.  SHE DIDN'T MIND WHEN HE WOULD BIKE RIDE WITH HER AND HER YOUNGER SISTER TO HIS SISTER'S HOUSE BECAUSE SHE KNEW I WOULD BE HOME WITH HER BABY SISTER.  GRADUALLY OVER 3-4MTHS SHE STARTED GOING BIKE RIDING ALONE WITH HER DAD AND REALLY ENJOYED THE TIME THEY HAD TOGETHER WITHOUT HER SISTERS.  I'M SURE IF YOUR SON SPENDS MORE ONE ON ONE TIME WITH HIS DAD, HE WILL LEARN TO RESPECT HIS DAD AND REALISE YOU BOTH LOVE HIM THE SAME.

Dad needs to assert the authority and set the boundary.

The adult needs to be seen as the adult not a challenge for the child to break.

Dont treat the child as an equal, not yet, this will come in later years when respect for each other will take over.