my son fights sleep..

Annaliesa
My son is almost 5 months old and does not nap more than 20 minutes during the day (if I'm lucky) and fights going to bed at night like his life depends on it. Even though he's overtired and cranky. We've been riding in the car to help him fall asleep but now he ends up waking up when getting back home and screaming and crying again. I don't know what else to do. I'm a FTM and I'm at a lose. HELP!