When the windshield wipers are operating, the brakes automatically pulsate to help keep
the main brake components dry and the pulsation is so minute that is undetectable by the driver.
There are several systems that contribute to rear - crash prevention, but the three
main components being tested here are: backup parking sensors (so you don't hit stuff backing straight), rear cross-traffic alert (so you don't hit stuff coming from the sides when backing up), and rear auto - emergency
braking (which saves your ass if you don't pay attention to the previous two).