I disagree. City driving at 25 mph is a lot more complicated and needs a lot more computing power than highway driving at 60-70 mph. City driving involves: handling the "dead zone" of intersection (square of pavement with no marking), poorly marked roads, pedestrians/cyclists/cars getting in your way, complex turn lanes, etc. By comparison highway driving is a piece of cake: clearly marked lanes, no sharp turns, no intersections, clear entry/exit ramps, all vehicles moving in the same direction, no pedestrians.