You can't just buy a horse and park it in a garage. You need to exercise it, give it vet care, shoes, feed it, deal with poop, etc. Or, pay someone to do that.
Unless you live in a place with dirt roads, or really love horses, I think a beater Toyota would win in terms of time and cost.
Well, you can't really just buy a beater car and park it in a garage. You have to perform maintenance on it, and the worst thing for a car is to just sit a long time.
A horse has the unique feature that it can create more horses, which is something a car doesn't do. Horses are also unique in being an appreciating asset, which cars are most definitely not.