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What would happen if you threw your car in reverse on the highway? Well, this answer from Howstuffworks is for a manual transmission, but I'm sure the same rules apply for my automatic.
"The reverse gear on any car with a manual transmission is an incredibly simple piece of machinery. There is a shaft that gets its power from the engine, and it has teeth on it that are used for reverse. There's another shaft that will drive the wheels, and it, too, has teeth on it that are used for reverse. To engage reverse, a gear literally gets pushed in between the two shafts to engage the two sets of teeth. It simply slides its teeth into the teeth on the two shafts and engages them."
The whole article (here).
