Is there such a thing? I want to cover up my d3.. So I can sleep sound at night knowing my car wont get jacked when i park it on the street.

Nope. No cover. Your best bet is to make one or find some kind of accessory by another company.

or get comprehensive insurance

If I'm worried, I used a hoodie that I put on my dashboard to drape down over the radio. It looks like the hoodie is on the dashboard instead of like I'm hiding something behind it.