The Optima Twin was replaced by the stretched Optima 4, thus named as it could seat four thanks to a longer wheelbase. The Optima 4 offered separately removable rear seats and was only sold with full equipment including tinted windows and seat belts front and rear. The Twin's engine was replaced with a three-cylinder diesel engine by British Perkins Engines, developing 9.6 kW (13 hp) at 3,600 rpm. As with the preceding Optima Twin, this version has front disc brakes to handle the more than doubled power and added weight.