Man Entering Occupied Cars In Portland

My mother always told me to lock my car doors while driving...

I always thought that was being a little too paranoid, but after seeing this news report, I'm thinking it might be a good idea. This is happening right here in Portland. And while police are saying that this man appears to be relatively harmless, it would still freak me out if a stranger got into my car while I was at a red light. Do you lock your doors while driving?