gistfile1.sql

BEGIN;
CREATE TABLE "cars_car" (
    "id" integer NOT NULL PRIMARY KEY,
    "model" varchar(200) NOT NULL,
    "color" varchar(200) NOT NULL
)
;
CREATE TABLE "cars_person_cars" (
    "id" integer NOT NULL PRIMARY KEY,
    "person_id" integer NOT NULL,
    "car_id" integer NOT NULL REFERENCES "cars_car" ("id"),
    UNIQUE ("person_id", "car_id")
)
;
CREATE TABLE "cars_person" (
    "id" integer NOT NULL PRIMARY KEY,
    "firstname" varchar(200) NOT NULL,
    "lastname" varchar(200) NOT NULL
)
;
COMMIT;

models.py

from modelmixins import ModelMixin

class Car(models.Model):
    model = models.CharField(max_length=200)
    color = models.CharField(max_length=200)

class CarOwner(ModelMixin):
    cars = models.ManyToManyField(Car)


class Person(models.Model, CarOwner):
    firstname = models.CharField(max_length=200)
    lastname = models.CharField(max_length=200)