Bikers Beware is a term we've heard that applies to bicyclists and motorcyclists watching out for cars. They are the 'smaller vehicle' so the phsyics of force when two collide would favor the larger vehicle.
Plus there's no protection from being thrown off one's motorcycle or bike so on that account the rider would be wiser to avoid 'close calls with cars' or even parts of a car, such as a Car Door.
That sounds easy yet likely we need reminder stickers and buzzers to 'check twice' before getting out of a car or even into a car.