Since I've just had to have this conversation again…
"If I had asked people what they wanted, they would have said faster horses."
– Henry Ford did not say this
This quote often gets thrown at product and user research people as a reason not to talk to customers and end-users. Here's me ranting at UX Bristol for three minutes on why it's foolish and wrong.
To summarise the three minute rant — Henry Ford didn't say it. The excellent Quote Investigator has a nice long post on this. The first reference to this quote being assigned to Ford is in a 2001 issue of Marketing Week. When Ford had been dead for a while.
Not that the line makes sense in any case. Because "faster" wasn't the selling point of cars over horses. Speed wasn't the problem. Spending huge amounts of money, time, and space on keeping horses alive and dealing with the literal horse shit was the problem.
Even better — it turns out that Henry Ford did say this:
"If there is any one secret of success, it lies in the ability to get the other person's point of view and see things from that person's angle as well as from your own"
— Henry Ford
Cited in Dale Carnegie's "How to Win Friends and Influence People" published in 1936 — when Ford was still alive.
TL;DR: Henry Ford did not say "If I had asked people what they wanted, they would have said faster horses". He pretty much said the exact opposite.