How did Mater even write that letter to Lightning?

Remember when Luigi wiped away the windows on his job's store? He used wire arms that either came from his windshield or from the inside of his windows (in Cars 1) Well, all the cars have wire arms and three sets of fingers tucked away inside their windows for doing things (You can clearly see that in Time Travel Mater when Stanley put a new Radiator boné, cap on McQueen). Mater probably found a pencil somewhere in the Japanese Hotel room and used his left or right wire arm to write the letter! We now know how these cars can build buildings!