Gloria on the back of the car

Not sure if it has been discussed on the board but how is it possible that she did not fly off the back of the car when Duke must have been doing over 100 mph half the time and doing spin outs - she never seemed to move out of position? Also, it must have been 120 degrees in the shade so sitting on the back of the car must have felt like sitting on hot coals. And, why did Ernie not sit on the back and have Gloria sit in the front seat?