The procedure for importing cars is different, depending on the country from where you are bringing the vehicle. If you are going to import from any of the GCC countries, then the following documents have to be submitted:
In case you are importing the car from anywhere else in the world (note: cars from Israel are not allowed), the following would apply:
1. A legal document proving the ownership of the vehicle, translated in Arabic and attested by the Saudi Embassy in the country from where you are going to export the car from.
2. Export declaration from the Customs of the exporting country.
3. Invoice and certificate of origin to be attached to the above export declaration.
4. A declaration from the police in the exporting country saying that the vehicle is not in the wanted list for criminal offences
The calculation of customs duty varies on case to case basis, but as a general guideline, you can follow what is given here. The latest price list of all major cars are available and this would be taken as the reference. Depending on the model and the age of the car, depreciation is calculated. Insurance and freight are added to this base value.
In case you are bringing in a vehicle which is less than the first six months of the model year, it is treated as a brand new vehicle. If you bring in a new vehicle in the second six months of its model year, the deduction is 2% per month or part of it. From the 2nd to the 5th of its model year, the deduction is 1% per month or part of it. For cars over 5 years, the maximum deduction is 60% of the original price from the beginning of the model year. The customs duty for cars is 5%.
If the above procedure is mind-boggling, then follow my simple advice. Forget about importing your car into the kingdom. You are better off buying a new car here, which you can sell it while going back. Why would you like to spend your time, money and energy going through all of this, when you don't even know for sure how long you would be here? Afterall, the only thing certain in Saudi Arabia is uncertainty!