While it would be foolhardy to rent a car to get around Japan's cities, driving is often the best way to tour the country's less-populated and off-the-beaten-track areas, such as Hokkaido or the San-in coast of Western Honshu. Japanese roads are generally of a good standard, with the vast majority of signs on main routes being in romaji as well as Japanese script. Although you'll have to pay pricey tolls to travel on the expressways, many other perfectly good roads are free and petrol is cheaper than in Europe, averaging ¥90 a litre. If you team up with a group of people, renting a car to tour a rural area over a couple of days can work out much better value than taking infrequent and expensive buses. It's often possible to rent cars for less than a day, too, for short trips.

There are car rental counters at all the major airports and train stations in cities and towns, with the main local companies being Nippon Rent-a-car, Toyota Rent-a-car, Mazda Rent-a-car, Japaren (which has a tie-up with Avis) and the JR-run Eki Rent-a-car. Budget and Hertz also have rental operations across Japan (although not as widely spread). For car rental firms' contact numbers, see the Listings sections in the relevant major cities. Rates, which vary little between companies and usually include unlimited mileage, start from around ¥6500 for the first 24 hours for the smallest type of car (a subcompact Minica, seating four people), plus ¥1000 insurance. It's possible to pay much more for flashier cars and, during the peak seasons of Golden Week, Obon and New Year, rates for all cars tend to increase.

To save map-reading headaches it's well worth enquiring about renting a car with a GPS (Global Positioning Satellite) navigation system; most of the major companies offer this as standard in their more expensive cars or can set it up for around ¥1000 extra per day. It's sometimes possible to get a English-version CD to work with the GPS - make sure you ask for this when you book.

Since you're unlikely to want to drive in any of the cities, often the best rental deals are through Eki Rent-a-car, which gives a discounted rate by combining the rental with a train ticket to the most convenient station for the area you wish to explore . With any rental company, it's also worth thinking about making a return trip, since one-way charges are high.

To rent a car you must have an international driver's licence as well as your national licence; if you've been in Japan for more than six months you'll need to apply for a Japanese licence. Driving is on the left, the same as in Britain, Ireland, Australia and most of Southeast Asia, and international traffic signals are used. It's a good idea to buy a copy of the bilingual Japan Road Atlas (¥2890) published by Shobunsha, which includes many helpful notes, such as the dates when some roads close during winter. If you're a member of an automobile association at home, the chances are that you'll qualify for reciprocal rights with the Japan Auto Federation, 3-5-8 Shiba-koen, Minato-ku, Tokyo 105 (tel 03/3436-2811), which publishes the English-language Rules of the Road book, detailing Japan's driving code.

The top speed limit in Japan is 80kph, which applies only on expressways, though drivers frequently exceed this and are rarely stopped by police. In cities, the limit is 40km/h, but you'll usually be lucky to be travelling at anything close to this rate, let alone speeding. To use the expressways you have to pay a toll , typically around ¥30 per kilometre, which can mount up to make the overall cost more expensive than taking a bus or train. On the Tokyo-Osaka route, for example, you'll shell out around ¥10,000 in tolls; for ¥3500 extra you could take the Shinkansen instead.

You shouldn't forget parking charges for towns and cities, either, where free roadside parking is virtually unheard of. There are always car parks close to main train stations; at some your vehicle will be loaded onto a rotating conveyor belt and whisked off to its parking spot. Reckon on ¥500 per hour for a central city car park and ¥300 per hour elsewhere. If you manage to locate a parking meter, take great care not to overstay the time paid for (usually around ¥300 per hour); some have mechanisms to trap cars, which will only be released once the fine has been paid directly into the meter. In rural areas, parking is not so much of a problem and rarely attracts a charge.

If you've drunk any alcohol at all, even the smallest amount, don't drive - it's illegal and if you're stopped by the police and breathalized you'll be in big trouble.