I get the impression that big American cars were popular throughout the Gulf during the 1970s and 1980s, so pre-1991 models were no doubt sold new in Iraq. I would venture to guess that 1990s models might have been bought secondhand from Jordan, which has always been a major trading partner of Iraq, sanctions notwithstanding.

Lastly, thousands upon thousands of used cars have flooded in since 2003. European cars have been shipped from Germany and the Netherlands (Iraq now seems to be full of first generation Vectras) and perhaps other countries. If I remember correctly, American cars from rich Gulf countries have come in through Kuwait.

Ingo knows about the used car export trade in Germany, so he might have something to add.