Sometimes my GPS thinks I'm on an adjacent road, especially when I'm on the freeway. Seems like that kind of error would be catastrophic in combination with a system like this. Also, what's the rationale for letting people go 10 over the limit? That's effectively admitting that people go 10 over the limit, and it's OK.
Michael Dukakis lost his home state of Massachusetts in the presidential race after he sicced the state police on drivers for exactly this during his campaign.
The law says to stay stopped at a stop sign for 3 seconds, and signal turns 800 feet in advance on the highway too, 600 feet on streets. (According to family who had their driving tests recently.)
Michael Dukakis did not have a great election night, but he did win his home state.
One reason among many: for passing, especially semis, without spending forever in their blind-spot
But as long as you're only going a few miles over the speed limit for a few moments, nobody's going to write you a ticket for it.
One of many situations where the law in theory and practical application differ, since officers are given discretion (read: ability to apply common sense) in their duties.
It's not a perfect system, but it's what we've got.
There's also what I've observed (not sure if there's an official name for it), that if you pass someone slowly, they will "lock tractor beams" onto you and start to match your speed. So you want to have a noticeable speed difference between your vehicles to prevent this.
If the car has different-sized tires than the ones it was originally designed for, there may be some discrepancies between the actual speed vs the speedometer readings, which is why there is some leeway in the speed limit to account for that margin of error.
"28171. (a) Commencing with the 2027 model year, every passenger vehicle... be equipped with an intelligent speed limiter system." and (b) "be capable of being temporarily disabled by the driver of the vehicle."
Also: (c) "shall be capable of being fully disabled by the manufacturer or a franchisee, but only as provided in Section 28172." (28172 is about EMS etc.).
I smell loopholes for me (politicians, and likely techies ;-), but not for thee.
Also interesting how GPS jammers haven't entered the chat yet?