Last year in January my cousin brothers and me went on a road trip from Chandigah - Delhi - Jaipur - Ajmer - Udaipur - Ahmedabad - Mumbai - Goa - Bangalore.
We had the time of our lives!
We encountered this guy somewhere in Karnataka, as you can see the car too quite some time to overtake him.
That's definitely the fastest I've seen any animal driven thing go. I don't think that's even a horse, looks like a donkey to me.