Explorer was extremely popular in late 90's and gas-guzzling as well. As a result many owners of old Explorers took advantage of the Cash for Clunkers program to trade-in their clunkers for a new car, plus 4500 dollars.
Imagine if they can trade-in their old clunkers with a new Explorer or F150, many would still buy the same vehicles.
Most Japanese models do not qualify as clunkers because of their relatively higher MPGs.