The best roads and highways are toll-roads. You can pay cash, or get a charge card (ETC) from the car rental company. They’re not cheap… it can cost $200-$300 to drive the length of the main island (Honshu), but the non-toll roads are often narrow, and winding, and mean you take significantly longer getting anywhere.
The GPS unit in your rental-car can be programmed by you to either avoid toll-roads, or to favor toll-roads.
And the GPS unit
- Can speak English (useful!)
- Accepts a landline phone-number as the destination (really useful!!)… so no need to type in a convoluted Japanese address on a Japanese language keypad.
Japan Tourist Tips 