I'm not so sure about that. Even if not used for traffic enforcement, there is a LOT of interest in the "IHVS" (Intelligent Highway - Vehicle Systems, maybe it's IVHS) community in having vehicle-specific data collection, for traffic management purposes. Basically all the preliminary work is done in terms of establishing data protocols, etc, lots of work on this between auto manufacturers, the federal DOT, state agencies, insurance companies, etc. I know when I was at MIT, there was a ton of money being put into it. The vision was very clearly that every vehicle would be "talking" to the highway system, and that big databases would be holding onto such data. The feds are handing out huge grants to the states to work on it (wouldn't be at all surprised if that's what let Missouri choose an expensive solution).

You'll soon start to see efforts to require GPS receivers and data links on all new cars. One policy paper I saw (from a state DOT, I think) suggested an ignition cutoff which would render the car inoperable if it went 30 minutes without a GPS update, for those who were thinking of blocking it....