G.♣.
Routines are helpful. But it's important that the routine be the right one for your child. When you determined his routine, did you watch him for a few days, follow his cues and then develop a routine based on his needs? Or did you decide on a routine and just start using it? If it was the latter, it's possible this simply isn't the right routine for your son.
Every child is different, and it's important to recognize your son's needs. Your son is at the age where he would probably do well with just one nap each day. Learning his cues is very important. Don't try to put him to bed because the clock says a certain time. Watch him. When he starts to yawn or rub his eyes, that's the time to bring him into your lap to read a book before putting him down.
Falling asleep in the car is extremely common at his age. In fact, many parents use the car to get their children to go to sleep. I don't think he's "trying to fall asleep in the car." If he gets sleepy in the car, it's because he's tired.
It sounds like you aren't paying attention to your child's natural sleep habits. If you could start noticing his pattern, you'll be better able to find the right routine.
ETA - I hear what you're saying in your SWH. There are other signs of a child being tired. I was trying to find some on-line, but all I could find were signs of being overtired. Maybe someone else knows?
Is he going to sleep at bedtime without too much trouble? If he is and he still gets up early, maybe he's going to bed earlier than he needs to. But if he is showing signs of being overtired, maybe he needs to go to bed earlier (I know it sounds crazy, but it could really help).
If it's just the waking in the middle of the night, that's a different story. That's actually totally normal, too. We just let our kids come into our bed. It's a bit of a pain in the butt sometimes, but we wanted our kids to know that they were always safe with us, even at night. Also, even though the sleep we got when they came into our bed wasn't as good as the sleep we had before they got there, it was still better than getting up with them or trying to make them go back to sleep. And it didn't last long. They both stopped coming into our bed when they were ready. And they are both excellent sleepers now (at 9 and almost 12).