Here’s why, and the answer is more fascinating than you think. It isn’t irrational behavior. It’s quite the opposite.
On the surface, it doesn’t make sense. A large vehicle speeds past them, and stationary stray dogs jump to their feet and run alonside the vehicle, attempting to run it down. But if the vehicle slows down and/or stops, they then stand off to the side and don’t attack the vehicle. This behavior appears so irrational you even have jokes and movie dialogues written about it.
Remember the joker in The Dark Knight Returns saying: “I’m like a dog chasing cars, I wouldn’t know what to do with one if I caught it”?
Here’s the real reason.
It’s their hunting instinct. Dogs are not wolves. Wolves have a different set of instincts because they are wild animals. But dogs we domesticated around 10000 years ago, so their instincts have evolved to live alongside us. For three-fourth of the time they’ve lived alongside us, we were primitive hunters. (Most of our rapid development and modernization happened only in the last 20,000 years.)
So a dog’s brain is still in the same place it was when they used to accompany us and help us hunt. We would wound a large animal, it would run away, we would chase it with our dogs, and the dogs would sprint after it and pull it down. Once it was stationary, their job was done and they would stand to the side while we would first eat, after which they would eat the leftovers.
So when a large noisy animal (a vehicle) is chased by them, once it stops (animal’s heart- the engine, is dead, because the animal is not making any noise) their job is done, and they will politely stand to the side. Biting the beast after it has stopped is like taking the first bite and is considered extremely disrespectful. It’s human masters will now refuse to eat the meat, and may even kill it for failing to respect the tribe hierarchy.
That is why they are more likely to start chasing you if you suddenly rev up your engine audibly. Because that sound, of the engine roaring (not unlike the bellowing of a morally wounded animal) triggers their chase drive.
Stray dogs are just doing their job with great sensitivity and attention to protocol, when they chase noisy metal animals to a standstill.
Credit : Quora
Picture Credit : Google