Coil Spring
WARNING: This page is about a different car, the 2003 Subaru Impreza and 2002 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
One having permanent strain should be replaced with a new one. When the vehicle posture is uneven, although there are no considerable reasons like tire puncture, uneven loading, etc., check the coil spring for its free length referring to specifications, cracks, etc., and replace it with a new one if defective.