I clear out my car about once a week. With two kids, and lots of errands, stuff builds up. I don't stress about it day-to-day though.
It's easy to do. I grab a garbage can, a laundry basket and my Handi-Vac. Garbage goes in the garbage, recycling and everything else into the laundry basket. Then, I vacuum up the crumbs, bits of leaves and twigs, and general crud.
Next step is the crucial one and this is where hoarders and clutterers can slip. You must, must, clear out the laundry basket immediately. Right away. Within 24 hours if you can't right away. I'm serious! Otherwise, it turns into a stash & dash. And then, it becomes and archeological dig.
I cleared out my car last night. I did not fully empty the laundry basket, because it was so late. But it'll be done before I go to sleep tonight.