( ( All ( they do ) ) ( ( is ( ( ( sit ( in ( a car ) ) ) and ) ( turn ( the ( steering wheel ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT All)) (SBAR (S (NP (PRP they)) (VP (VBP do))))) (VP (VBZ is) (VP (VP (VB sit) (PP (IN in) (NP (DT a) (NN car)))) (CC and) (VP (VB turn) (NP (DT the) (NN steering) (NN wheel))))) (. .)))
All they do is sit in a car and turn the steering wheel.
(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.