Permanent residents can not bring in a car without tax, only temporary residents can, as the point is if you don't pay the tax you will need to take the car out. (ie. the car is in the country only temporarily). If you have a permanent visa, that assumes you will stay & so will the car. Expect a nice bill of about 78% of the value imposed by the authorities and not on the value you declare. We just went through this & we decided not to bring the car.
Actually this is not correct, I brought in a car as a temporary resident and it's registered there now without paying duties assuming in the end you become a permanent resident. You can also bring in your personal effects as a temporary resident and avoid duties assuming you become a permanent resident.
I don't know if you can do it now after you have become a permanent resident(my guess is that you won't be able to). You would have to check this out.
As a practical matter I wouldn't recommend people bring in a car from the states or elsewhere. Unless it a very valuable car the shipping costs and all the hassles you will encounter make this not a very good option in my opinion. My guess is that the cost of shipping a car here from the states could be $5,000 or more. In my case we drove the car in from a nearby country. Believe me the hassles this involves can not be minimized.
You can bring in your personal effects as a temporary resident. The way it works is you post a bond equal to the amount of the duty, in my case $4,000. You then buy an insurance policy that garantees payment of the duty if you don't get permanent residency(never figured this out since they all ready have the money upfront). The insurance cost me $400 a year and since permanent residency takes two years the total was $800. Once we had the permanent residency we got back the $4000.
Personally, I wouldn't recommend doing this unless you have some very good furniture, etc., the cost of transporting here makes just buying new stuff in Argentina more practical for most people.