We've had questions like this (in fact, I think we've had one almost identical) and the problem is lack of sufficient definition of the requirements. Do you want fastest unladen horse in a gallop, or fastest horse that can carry a lightweight, unburdened rider all day, or fastest "family horse" that can pull a cart with 2 adults and 2.4 children for a one hour commute in the morning and same in the evening? For that matter, you are indeed crashing this worldbuilding forum with a question that has - so far - no worldbuilding context. Details and context, please.

The top speed of a race horse is about 70 km/h over a short distance; over a not quite so short distance a decent but not exceptional race horse can gallop at 48 km/h. The top speed of a Ford Model T is 42 km/h. Sorry but I cannot be be bothered to convert to olde skoole meddy evalle units of measurement.

@KerrAvon2055 what they want is what they have but faster, whether plough horse, cart horse or carriage horse. They want the familiar, upgraded.

@Separatrix sprinters and endurance runners are quite different, whether horses or people. Ability to carry or pull a load (and how much of a load) changes things massively too - from what I recall of the previous question, the sprinting, no load-bearing "horse" had a very strong and unsurprising resemblance to a cheetah! And that's before even looking at what terrain the "horse" is optimised for - two of the answers are proposing skates that would work badly or not at all except on sealed roads.

Came for horse husbandry question - stayed for all the mechanical hackery suggested.

Dangle a carrot in front? Is that not how we make a faster horse? :P More seriously though, I'm surprised no answer so far has covered plain old selective breeding.

Henry Ford's customers did NOT want "faster horses". What they wanted were carriages that were cheaper in both purchase cost and maintenance, especially when they were used less often (i.e., operating costs should scale better with actual usage). The big problem with horses is that they still cost pretty much the same (in both $$ and effort/time) whether you used them or not. So unless you were rich or a farmer, they were impractical.

It's a joke @RBarryYoung – there's a "quote" that goes that Henry Ford once said, "If I'd asked my customers what they wanted, they'd have said a faster horse"

@RBarryYoung I see where this is going... what customers really need is a horse sharing program that will spread the full utilization of one horse out over multiple customers to allow each customer's cost to be proportional to actual usage!

The horse app, Gallopr

Do you have a specific goal for how many horsepower this improved horse should get?

Some horses have managed to get themselves loaded onto jets and as a result, move very fast!

Really? How is 'do my job for me' acceptable?

What make's you think Ford's research department thought customers wanted faster horses? If they had, what makes you think early cars were faster than horses?

Jones from market research told me at the weekly scrum

VTC:Needs More Focus, which is defined as follows, "This question currently includes multiple questions in one. It should focus on one problem only." Asking more than one question per post is literally a reason to close the question. ADDENDUM: It's also a duplicate of this and likely a number of others.

@KerrAvon2055 Another option: "You want a truck - elephants!"

Is it an African or European horse?

@Michael They already had horse sharing