Earlier quoted context omitted.
How much of this is also a reflection of autonomous navigation, risk avoidance, and proceeding at a deliberate pace? While we've got vehicles on Earth which can navigate established highways at, well, highway speed (Google cars), the established road network on Mars is substantially less extensive, and the downside risks (in terms of mission outcome) of even a small mishap on Mars would be very high. So: for both eng…
Another reason why the rovers are slower than cars: cars have air-breathing engines. On Mars, your propulsion system needs to be totally self-contained, or else solar powered.
There are all-electric vehicles with considerably better than cm/s speeds.