There are two terminals at Narita, so before you travel to Narita, make sure you know which terminal you should go to. Terminal use is decided by airline. A rule of thumb is that most of the Japanese airlines (ANA, JAL, etc.) use Terminal Two, and most of the other airlines use Terminal One. However, the airlines which have partnerships with the Japanese airlines also use Terminal Two, so ring and check.
Narita has been subjected to attacks by angry protestors in the past, so at the gate there is a security check. You'll need to show your passports and probably open the back of your car. So far I've never had my luggage searched though.
Parking at Narita itself is extremely expensive. Around the airport there are lots of private parking facitilies with names like USA Parking or Kaigai Parking. You pay them a fee in advance and you can leave your car in their car park for a week or two during your trip. They usually have a bus service which takes you from the car park to the airport. They usually need a reservation in advance. Price competition is fierce.
- Narita Airport
- IACE Travel's page on Parking near Narita Airport
- Online reservations for parking at Narita Airport