A friend of mine had a geriatric bulldog with extreme hip displasia. We were at a farm one day, and my friend drove to town, leaving the bulldog with me. She (the bulldog) took it in her head to go find her mistress. She set out at a trot that quickly left me in the dust, and I was in pretty good shape at the time.
Greyhounds can run fast for short distances, but some small dogs, like Jack Russells for instance, can run with the horses and the hounds all day long.
OK, in the interest of factual answers, I took him for a run.
He started out at 23mph but dropped down to 20 after about 1/10th of a mile. He never dropped below 20 for the rest of the half mile. He hasn’t been run in a few years so I didn’t want to kill him or blister his pads, but he’s standing right here and isn’t even breathing hard (and wasn’t straining during the run).
I was pretty confident that I hadn’t misremembered his running speed. Many of my friends have been along when I’d run him going to the lake to burn off some energy before we went fishing and have been surprised at how far he could run, we never really thought that his speed was noteworthy.
Ah, my mistake. I don’t know how didn’t pick up on the “running beside the truck” part. Sorry.
No problem, I didn’t know it made a difference. Sort of like a Greyhound after the “rabbit” at the track.
He’s perked up, he must have enjoyed it.
He’s a good little fellow.
It’s important to remember that greyhounds are sprinters, not marathon runners. Sure, my dog could run 35 mph for a half mile or so, but much more than that and she’s done. In fact, most greyhounds are good with a couple of walks a day, they spend the rest of the day sleeping.
And just as an FYI…
The group I work with (www.gpa-nw.org) prefers to call our dogs “retired” as opposed to rescued, because while there are some breeders out there who don’t treat their dogs well, a great majority of them do their absolute best to help the dogs before, during, and after their racing career.
So… anyway, if you are looking for a dog, greyhounds are fantastic!
The only difference is that if you took him for runs on foot it would make you soooome runner. 
You’ve made me really happy that I didn’t have to stop this car and remind you to do pictures! 