You do know that thinking about a panic attack can induce one right? (first hand experience) So can anticipating an anxious situation make your anxiety skyrocket. (also first hand).... Idk if this one is possible because I dont suffer from paranoia, but once when I was high, I was worried I would become paranoid, and BAM! I was paranoid. So maybe even that one applies here.

My point?

Chill out. Breath.

You already do all the reality safety-checking before you start driving. What more can you do, hire a psychic before each drive?
You are driving yourself nuts with worry alone.

If you see something, you see something. If it freaks you out alot, so much so that you are unsure of its realness, then pull over and do breathing exercises until you realize it was never there in the first place.

Seriously chill, you'll give yourself a coronary worrying about something that may or may not happen, or may or may not have a negative impact on you