Abstract: A non-linear non-circular coiled spring comprises a first coil portion of rectangular cross-section having a lateral length “a” and a longitudinal length “b”, a second coil portion of rectangular in cross-section having a lateral length “b” and a longitudinal length “a”, and a transition coil portion connecting the first coil portion and the second coil portion by gradually twisting one of first and second coil portions toward the other of first and second portions. The non-linear non-circular coiled spring is adapted to be used as a car suspension or a machine spring.