(a)

The change in energy of the transferred charge is given by:

where
q is the charge transferred
is the potential difference between the ground and the clouds
Here we have


So the change in energy is

(b) 7921 m/s
If the energy released is used to accelerate the car from rest, than its final kinetic energy would be

where
m = 950 kg is the mass of the car
v is the final speed of the car
Here the energy given to the car is

Therefore by re-arranging the equation, we find the final speed of the car:
