why not? Because some people would choose not to buy the car if they had to drive it at the speed limit across the empty expanses that make up their favorite ro

why not? Because some people would choose not to buy the car if they had to drive it at the speed limit across the empty expanses that make up their favorite road trip, or through areas where the limit is lower than it "ought" to be. I think speed limits are set based on safety concerns more than environmental ones, and in that sense self driving cars should probably be allowed more speed not less. I claim without evidence that the greater contributor to inefficient fuel use is needlessly abrupt acceleration and deceleration, rather than top speed, and hopefully self driving cars do help with that.