Re: in sync?
@TerryB- Oh, you could do it lots of ways. but retrofiting millions of cars to be connected seems far more expensive than a stick on the windshield.
As for the gas stations being connected, most should be in the US. Not only do they need it for point of sale, but most gas stations in most states have other needs including their supply monitors that connect to their home office, communicating with the state if they do inspection, other stuff with a national home office, etc.
I think the internet part is the easy part. As for the back end, to me, if you've already got a robust DMV system that talks to the police (as most states do, you're really only talking about adding a few lines to a database. It isn't a small task, but it is a managable one.