Definitely not 660cc engines, they are just mainly normal commuter cars. Alot of wagons is what I notice going from osaka to Tokyo, Osaka has a thing for vans.

I'd hazard the mean engine displacement is 2000cc with commons being 1 6. 1 8. 2.0 and 2.3. I've also seen lifted chevys in Japan (super rare obvs) so it's all relative.