More seriously: Almost all cars in Germany are limited to 250km/h (155 mph). Higher limits for more powerful cars are also found in the 280-290 km/h (173-180 mph) range.
So, de facto, even in Germany speed limiters have been a thing for decades. The discussion should thus be more about the limit, rather than the device itself.
Obviously this is different than imposing a „+10 mph“ limit, since the car would have to know the speed limit of the current road.
More seriously: Almost all cars in Germany are limited to 250km/h (155 mph). Higher limits for more powerful cars are also found in the 280-290 km/h (173-180 mph) range.
So, de facto, even in Germany speed limiters have been a thing for decades. The discussion should thus be more about the limit, rather than the device itself.
Obviously this is different than imposing a „+10 mph“ limit, since the car would have to know the speed limit of the current road.