( ( The idea ) ( ( was ( to ( make ( ( the cars ) ( turn ( easier ( because ( of ( ( better traction ) ( on ( ( ( the ( front wheels ) ) , ) ( caused ( by ( more ( aerodynamic downforce ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN idea)) (VP (VBD was) (S (VP (TO to) (VP (VB make) (S (NP (DT the) (NNS cars)) (VP (VB turn) (ADJP (ADJP (JJR easier)) (PP (RB because) (IN of) (ADJP (ADJP (RBR better) (JJ traction)) (PP (IN on) (NP (NP (DT the) (JJ front) (NNS wheels)) (, ,) (VP (VBN caused) (PP (IN by) (NP (JJR more) (JJ aerodynamic) (NN downforce))))))))))))))) (. .)))
The idea was to make the cars turn easier because of better traction on the front wheels, caused by  more aerodynamic downforce.
(ROOT (S (NP (DT The) (NN turning) (NN driveshaft)) (VP (VBZ causes) (NP (NP (DT the) (NNS wheels)) (PP (IN of) (NP (DT the) (NN car) (S (VP (TO to) (VP (VB turn)))))))) (. .)))
The turning driveshaft causes the wheels of the car to turn.