Once (begin assumption here) autonomous cars become the norm I don't think this will be a problem. The reason speed limits exist at all is because we don't want

Once (begin assumption here) autonomous cars become the norm I don't think this will be a problem. The reason speed limits exist at all is because we don't want people who are not physically capable of driving at that speed (poor eyesight, bad reflexes, etc....) to try, so we set the limit at a level where we think everyone should be reasonably ok in that situation. But if all cars are run by computers, we can raise speed limits considerably, since reaction time, sleeplessness, stupidity, etc... are all non-factors anymore. The only problem is whether or not your car can actually go as fast as everyone else, but for that we can set up fast and slow lanes similar to the somewhat unofficial way things go on the highway now (faster the closer to the leftmost lane you are).