http://en.wikipedia.org/wiki/Subaru_Impreza#WRX
"Subaru adopted the name "WRX" to stand for "World Rally eXperimental"
(in some places WRX stands for "World Rally Cross") as all WRX versions
(1992 to present) feature rally inspired technology, including all wheel
drive, stiffened suspensions and turbocharged four cylinder engines."