4.02439 from partner siteOne way transfers from the end point (Ketetahi) to the start of the Crossing (Mangatepopo). Free, secure all day parking.
This is the popular hassle free and cheapest option if you have your own car.
You will do the 6-8 hour hike back to your car in the car park which is located a short walk from the end of the Tongariro Crossing. No need for afternoon shuttle transfers.