The fastest speed limit on Big Island is 60mph, but most of the roads are 25 to 35mph. Drivers should know that it is easy to speed here if you’re not paying attention, as speed limits frequently change on the roads. Many of the local police use private, unmarked vehicles with only a small blue light on top to distinguish them from other cars, and you might not notice them until it’s too late to avoid a ticket. Search rental cars on KAYAK