As always, "It depends". The speeds listed above (In km/hour, as is proper) are a good guideline, but enforcement is trickier.
In a 'plex, the majority of cars are electric and tied in with GridGuide ™. This got more common after Crash 2.0 and the wireless Matrix, natch. GridGuide ™ will make certain that you say in the right speed band as well as give you directions or, if you'd like, your Pilot program is perfectly capable of driving for you, which many people enjoy. Get in your car, tell it where you want to go, then fire up your commlink so that you can enjoy the ride while reading or updating your MeFeed. Many people never even learn to drive, because, well, why would you? The car drives itself. Themanual override is there, so you can disengage the pilot and do your own thing, but there's not much of a reason to do so. Traffic that moves in unison with lights are vastly more efficient, and you'll never break a law, so let it handle things.
Law enforcement for traffic violations uses a lot of drones. Drone cameras at red lights, for instance, peg you if you run the light, while GridGuide itself keeps tabs on the streets and will ping you when you're going to fast, to advise you to slow down or be fined. Ignore it, and the tickets start dropping in. Ignore them, and the local police are called in to stop a reckless driver. Neat bonus? GridGuide will pull all the cars to one side of the road, so that the pursuit cars can catch up to you easier and with less risk of an accident. Helicopters and flying drones can be called in for major moving issues, and its a simple thing to tag a car with paint and some RFID tags so that you can follow anywhere it goes.
Now, once you get out of the downtown area and the better middle class neighborhoods, you get more people on public transport and driving cheaper (often used, sometimes just scoot-like) Less GridGuide here, since the network's less reliable, and more people driving themselves. Once you get to the Barrens, the only cars you'll see are likely to be rusted-out gas-guzzlers from 20+ years ago or shiney new vehicles for successful crooks. When the leader of the Bloodfangs gang parks his shiney new SUV in the road, nobody touches it. Easy way to find people, that.