Update ICar.java

[yann-gael]

No description provided.

[singhsatnam]

I have made some changes to conform to your suggestions. However, I would like your input on the following as I was not able to figure out a way to do this:
--I wanted to allow a method in "SuperCar" (or its super) to add some options, even after initializing the object of type ICar in TestPurchase. You can find it commented in the class "SuperCar". Presently, this is achieved in the class TestPurchase while creating the object itself.