Simplify the following text for a Grade 5 native English-speaking person.
Original: Displacement can also be very small , as found in kei cars sold in Japan , such as the Subaru EN series ; engines that started out at 550 cc and are currently at 660 cc , with variable valve timing , DOHC and superchargers resulting in engines that produce 65 P.
Simplified: Displacement can also be very small . Some cars sold in Japan have engines that are only 660 cc .