How a moving car becomes electrically charged? Car has been electrically charged as it travels along the road.how is this possible?
 A: If the tires aren't conductive enough, the asphalt/concrete surface of the
road acts like fur, and the tires act like amber, and charge separation
occurs at the contact point, then the movement of the wheel does work on
the separated charge.   Charge repels, leaking through the axle to the car body,
accumulates on the outer shell of the car.  Basically, the tires (on the interior
of the wheel well) are inside a Faraday cup, so this charge will always
migrate to the outside.
Then the (newly discharged) tire surface comes back into contact with the
road, and the cycle repeats.
Tires are black because of carbon (conductive) added particles, said to
make the 'charge separation' event mainly not happen.
A: Look up Triboelectricity.
When objects come into contact with one another, temporary chemical bonds form between the touching objects. When these are afterwards broken mechanically, they can leave the two objects with an surfeit / dearth of electrons on either side of the broken bond. 
This process happens continuously for moving objects like a car and particularly for aeroplanes. Air and road continually make and break contact with the vehicle through the latter's friction with the former.
