You can register a car no matter how old it is as long as it passes emissions and it Skakken inspection. Shakken is something that is required every two years. You must take your car to have it inspected and if there arent any leaks, seepage, tires and other safety items are still good then you pass and get you registration. It cost's almost 1000 USD to have it done. Not including the parts you may have to repair or replace just to get it to pass inspection. It's way more stringent then anything in the US, yes even California. And I registered cars in both California and Japan and here in Japan it is a real pain in the ass. Especially if you have an old car like mine.