The guy that drives the newspaper delivery truck from the "city" 60 miles away had never hit a deer. Keep in mind he's driving at like 3 in the morning over some BACK roads. He installed two whistles and has hit three since. I'd have to say that they work pretty good!

Also, fwiw, ANY road kill should be left for the buzzards. The trauma makes the meat undesirable if not downright poisonous.