Dogs - had a dog when I was in college who loved trucks. As a young puppy, I let him ride around at 20 mph or so on dirt roads. He jumped out once, rolled, bawled for me to come get him (he was unhurt, just scared), and after that he KNEW to stay in.
Over the next 13 years, he road thousands of miles in the back of the pickup. If there was a toolbox, he'd ride on top of it. If we hauled hay, he'd find a way to the top and ride there. When I worked for the Division of Wildlife in Utah, the toolboxes came to within a few inches of the top of the cab, and he rode there.
I later went in the US Air Force, and he followed me to the Philippines & England and back. He was pushing 14 when he died, which is pretty respectable for a 100 lb dog.
I have never tried it with another dog. My current dogs sometimes ride in the back with the wife & daughter for the 1/2 mile trip to the desert - then they go run for 30 minutes or so. But we're on back roads and don't go above 25 mph. I would never
trust them by themselves. But Chris? He knew.
He's NOT the Border Collie, but he DID love catching snowballs. He was 12 in the picture below: