Yeah, it's the same in Europe. And because you can easily just drive through into the next country, you might forget you've entered another country with different speed limits and laws. ;)
Germany is very similar to Japan. You can go 10 km/h above the speed limit and it's still ok, not more than that, though.
But as we have the Autobahn in Germany we cannot only go as fast as our cars can go, but we also have toll-free highways. I don't care soooo much about the speed limits, but I hate when I have to pay for using certain roads in Japan. ;)