Autozam AZ-1 / Suzuki Cara Rear Bumper
Here you will find all the rear bumpers you could possibly get for your car!
Original
The original panels were injection molded plastic. Stock bumper looks like this.
AUTOGIANO
Fiberglass rear bumper
It can also have a diffuser attachment. Can get new from AUTOGIANO.
https://autogiano.com/list/ma/list_mreb.html
RICE ROCKET R
Part of the RICE ROCKET R body kit. Has two vent holes not sure if you have to modify the bumper reinforcement to improve the airflow.