I have this idea that I'll get Bosch 9-DoF sensors onto every lane of every road, at least twice a month, then any other thing on a road can use a Shazam - like waveform lookup to determine where they are.
I didn't come up with this for dead reckoning, it's more for, um, autonomous cars to be able to avoid potholes and stuff.
What i started building is for a highly unlikely scenario which is ; no internet + no GPS + no cell tower.