Try this site:
http://www.customs.gov.au/site/page....e_page_id=5095
It tells this and more:
importing a motor vehicle
Any person may import a motor vehicle or a motorcycle into Australia as directed in the section Motor Vehicle Standards Act detailed below.
If you plan to drive the vehicle on Australia's roads it is essential that you contact the Vehicle Safety Standards Branch before importing the vehicle to ensure that the vehicle can meet the safety requirements and to obtain a permission to import the vehicle.
All privately imported vehicles are subject to the same rates of Customs duty and Goods and Services Tax (GST) and, where applicable, Luxury Car Tax (LCT) as commercially imported vehicles. The Customs duty is based on the Customs value of the vehicle.
The rate of Customs duty payable is that which applies to the particular type of vehicle on the date it is entered for Customs purposes in Australia. GST and, where applicable, LCT applies at the date you import the vehicle into Australia. Without a permission to import, which can be obtained from the Vehicle Safety Standards Branch, a special duty of $12,000 may apply.
As Customs duty varies according to vehicle design and value, and is subject to change, you should contact a Customs office before importing any vehicle into Australia.
Prior to making a decision to import your vehicle you should take into account the costs involved in the process such as: freight, Customs duties and entry processing charges, steam cleaning for quarantine purposes, other wharf and transport charges and any costs involved in having the vehicle meet state or territory registration requirements (whether your vehicle will indeed meet these requirements should be checked prior to importation).
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Valuing your vehicle for Customs purposes
The Customs value of imported private motor vehicles and motor cycles (whether new or used) is assessed in the following way:
The Transaction Value Method
The Customs value of new or second hand privately imported motor vehicles or motor cycles will ordinarily be calculated using the "transaction value" method. Under this method the Customs value is based on the "price actually paid or payable" for the vehicle or cycle in a bona fide sale where the price is not influenced by any other factor.
This method will be used where the importer can show that the vehicle or cycle was purchased to be exported to Australia. The transaction value method will not be used where there is insufficient or unreliable information regarding the purchase.
In determining the Customs Value, certain adjustments may be made to the price paid by the importer to have the vehicle or cycle brought to Australia (eg. the deduction of overseas freight and insurance).
Alternate Methods of Valuation
When the "transaction value" method cannot be used to determine Customs Value, the alternate methods of valuation, as set out in Section 159 of the Customs Act will be applied in sequential order.
Where the Fall-Back alternate method is used, Customs will usually accept as the basis for determining the Customs Value, the landed cost of the vehicle or cycle in Australia as assessed by a person qualified in valuing such vehicles and cycles. Customs may then make certain deductions to determine the Customs Value of the vehicle or cycle.
The valuation procedures outlined above are applied by Customs to privately imported motor vehicles and motor cycles purchased by the importer on or after 2 March 1998. The previous set of valuation guidelines used for motor vehicles and motor cycles purchased by the importer prior to 2 March 1998 are contained in the 'Guide to the Importation of Privately Owned Motor Vehicles and Motor Cycles' included below.
Conversion to Australian currency
The Customs value of your vehicle is calculated in Australian dollars. Where it is necessary to convert any prices, costs, etc. from a foreign currency to Australian dollars, the conversion will be based on that rate of exchange in effect in Australia on the date of exportation of your vehicle to Australia.
Guide to the Importation of Privately Owned Motor Vehicles or Motor Cycles(222KB)
Customs Valuation of Imported Goods Factsheet (42KB)
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Concessions for tourists and temporary residents
As a tourist or temporary resident, you may bring a motor vehicle or a motorcycle and attached trailer or a caravan to Australia for a period of up to 12 months (or longer under certain circumstances) without paying duty on them, provided they are subsequently exported from Australia.
For this concession to apply, you will need one of the following:
a Carnet De Passages en Douanes issued by an overseas organisation which has a reciprocal arrangement with the Australian Automobile Association, or
a cash or bank security, equal to the amount of duty and GST and, where applicable, LCT otherwise payable.
If your vehicle is stolen, damaged or destroyed whilst you are in Australia you should notify Customs as soon as possible at your original port of arrival.
All fittings and accessories imported with your motor vehicle, motorcycle, trailer or caravan must also be exported with that same vehicle.
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Quarantine
To prevent the entry of diseases, noxious weeds and insect pests into Australia, Quarantine authorities inspect all vehicles on arrival and may require them to be properly cleaned. This is usually effected by steam cleaning. You should remove all soil and any other matter from your vehicle (including the underside) prior to exportation to Australia.