MySQL and PHP question

Why wont my code work?

Code and MySQL tables are below

CREATE TABLE cars ( car_ID int AUTO_INCREMENT, car_Name varchar(60), car_reg int, car_Stock int, car_Price float, PRIMARY KEY (car_ID) );

CREATE TABLE figures ( Model_ID varchar(60), Person_ID int NOT NULL, Cost int NOT NULL, figure_Sales_ID INT NOT NULL, Date_Purchased DATE NOT NULL, Sale_Price float, PRIMARY KEY (Model_ID) FOREIGN KEY (figure_Sales_ID) REFERENCES cars(car_ID) );

best carrs