[ficke]

Here is the long answer.
'Grey Market' description is used to describe to cars modified individually to meet US safety and pollution laws.
25 year old and older cars imported into the US are not grey market, So if today you bought a ROW 1988 Turbo in Germany and imported it to the US it would not be considered a 'Grey Market' car, because it is over 25 years old and does not need to be modified to bring into the states.
Also cars that did not have to be modified to be imported even at the time, like my 1968 911S, are not grey market.
You did not have to modify cars up to 73 to bring into the US. Like with side impact beams in the doors etc., because those laws did not go into effect until 1974.
70-73 Porsche 911's are not 'Grey Market' cars, and never were. Because they did not need to be modified even in the day to bring into the US by individuals.
Many people put a premium on non US pre 74 911's for their unique features here like, French required yellow head lights or German marker lights. The Euro 1968 911s that do not have smog pumps or side marker lights. These all ad to the value of the car.