Current cars (BMW, Mercedes-Benz) already have that. There's a camera that recognizes signs and warns you if you're above the limit. See http://www.bmw.com/com/

Current cars (BMW, Mercedes-Benz) already have that. There's a camera that recognizes signs and warns you if you're above the limit. See http://www.bmw.com/com/en/newvehicles/3series/sedan/2011/showroom/safety/traffic_sign_recognition.html#t=l http://www.bmw.com/com/en/newvehicles/3series/sedan/2011/sho...