Having a follow-the-speed-limit setting for autopilot would probably not be a popular feature; tangentially, see Drivers Push Tesla’s Autopilot Beyond Its Abilities (MIT Technology Review)
"The most exciting new feature for Tesla owners is its autopilot. Nimble enough to keep the car within its lane and intelligent enough to sense other drivers, the recent update to Tesla's software gives customers a first, early taste of what driverless driving feels like. But the Tesla evidently isn't smart enough to outwit speed traps — yet.Tesla’s autopilot gets pulled over for doing 75 in a 60 - The Washington Post
In a test-drive showing off the autopilot control, Drag Times took the latest Tesla software for a spin. On a stretch of Interstate 95, however, the Tesla got pulled over for doing 75 mph in a 60 mph zone. Oops."