You should be aware of a number of important traffic laws before you hit the road with your cheap Dallas car rental. In Dallas, it is against the law to use a phone while driving. Drivers in Dallas are always required to follow the posted speed limits on designated roadways. When driving your rental automobile on highways without speed limit signs, it is advised that you adhere to the overall speed restrictions specified by the traffic authorities. On every unpaved road in Dallas, keep your speed to 30 mph or less. In school zones, the top speed restriction on all roads in Dallas is 20 mph. The main prerequisite is that all drivers of rental cars follow the 70 mph maximum speed limit on Dallas' rural interstate roads.