Re: If Google wants to limit the speed of their test cars/prototypes to 25 mph....
> I remember learning about minimum speed road sign during my learning of the highway code but in 40 years of driving, sometimes up to 80,000 miles per year, I don't think I've ever seen one out in the wild.
Whereabouts? In Europe, every motorway has a minimum speed, though they're not posted--you need to know it from the local traffic code. Alpine tunnels also have minimum speeds, as do multilane mountain roads, when a slow lane is present. The sign is a blue circle with the minimum speed in white letters inside.