[...]
class Car {
    public Engine getEngine(int fuelCapacity) {
        if (fuelCapacity == 11) {
            class OttoEngine implements Engine {
                private int fuelCapacity = 11;

                public int getFuelCapacity() {
                    return fuelCapacity;
                }
            }

            return new OttoEngine();
        }

        return null;
    }
}
[...]