The Shu Roo product was posited to repel kangaroos using an ultrasonic tone, however an evaluation by Bender (2001) found that Shu Roo resulted in no difference to kangaroo vigilance response, flight response, or the number of animals actually hit when compared to control vehicles not fitted with the device.

Do shoo roos actually work?

No, they don't. Tests have shown that kangaroos don't react at all to the high frequency sounds they emit. They aren't loud enough for the sound to project forward of a moving vehicle's road noise… and can only be heard when the vehicle's passing.

Do car whistles work?

Once attached to the front bumper or grill of your car, they're supposed to emit a sound that alerts deer and scares them off. ... A 2007 study from the University of Georgia also found deer whistles are "likely not effective in altering deer behavior along roadways to prevent collisions."