I've been putting a lot of thought into car carry recently, so I'll share with you what I've come up with. First of all, I ended up ruling out a dashboard holster for myself. Anything placed on the dash gets incredibly hot, even during short trips. The sun beating down can also cause quite a bit of damage in the long run. I'd be more concerned about the holster than the gun, but still. Oh, and almost all velcro I've comeacross specifically says "Not for use on dashboards or in direct sunlight", or some variation of that.
I really don't see any problem with carrying in a belt holster. If you're openly carrying, and sit down in a restaurant booth, no one can see your gun. That doesn't make it concealed, however. The same should apply to your car. You're not intentionally concealing the handgun by sitting in your vehicle. It is still clearly visible on your person.
On top of that, you really shouldn't be getting pulled over in the first place . IF you do get pulled, you should have plenty of time to safely move the gun from your holster to the passenger seat. Moving your gun every time you get in and out of your car is creating a situation similar to the airline pilots that have to move their handgun every time they leave the cockpit. Eventually someones going to shoot a hole in the floor, if not yourself. I say just leave it in the holster.
*I am not a lawyer, but this is the advice that I live by.