Disappearing off the radar...
Amazingly, as soon as you put a tracker car inside a welded steel crate, the signal can't get out. Who would have thought it!
The words "disappear off the radar" in the original article are really going to get some stupid people jumping to conclusions, and was a very poor choice of phrase. Then again I would expect nothing less from someone who has written a report stating the blindingly obvious. Incidentally, military P-code systems use a different frequency with a much wider signal spread based around a different centre frequency and wouldn't be blocked with these jammers.
The interesting stuff will be when someone hacks together some FPGA gubbins and a transmitter and generates fake location info. That will really put the cat among the pigeons. It will royally mess up road charging because you could make your car believe it was hundreds of miles away. For that matter you could make other people's cars believe they were in the London charging zone, or suddenly doing 90mph. Sideways.