Don't take his car and boat connection, you will die after a long time. It often takes more than ten hours to run 500 kilometers, just by car. The air conditioner in the car can freeze you to death, but you can't adjust it yet. Add some money to buy a ticket of AirAsia or Bird Airlines, which is not expensive and suffers a lot less.
Anyway, I won't go to South Island by bus or boat again.