As the title says, can anyone guess? John
XR-7 can be anything you like - no one has a clue. Even the original marketing material that Jim Pinkerton has doesn’t shed any light on why or how they picked it. I guess it sounded a bit like XK-E or XJ6 or it could have been some form of experimental version naming
It has since morphed into a whole naming convention for Ford sports versions of production vehicles
The code ? do you mean the in house designation that Ford used on the Cougar project ? if so, it´s T 7
Yes, and you’re correct, T7. Congrats 
. John
Leon, you have a third of the answer right, “experimental”. I saw on the internet a while back what it stood for (at least to me, it makes sense) but for the life of me I can’t find it any more. 
John
This one?
“Mercury now had its own pony car, and set out to make a serious dent in that market in the late Sixties. The Cougar XR7 (XR for “experimental racing”, and the “7” from the early “T-7” designation?) was introduced as a luxury trim package with overhead consoles, toggle switches, leather seats, and wood grained steering wheels.”
http://www.fordcarz.com/classic-mercury-cars/classic-mercury-cougar.html
I don’t have any idea what XR7 was supposed to stand for, but give me your opinions on this. Since the XR7 package had nothing to do with performance why would it stand for “experimental racing”? It sounds like someone was reaching with that definition.
Maybe “XR7” stands for “looks more European, you know, like a Jaguar?”. They used to abbreviate things differently back then, obviously.
XR stands for xtra rich luxury…never mind that would be ER-7. 
Steven
There is endless action like this in the Automotive industry. Creative marketing perhaps.
XR7, X19, Camero, Corvette, MKX, MKZ, Ciera, and on and on and…
At least the XR7 also had a real names in, “Cougar” and “Mercury”. In the showroom XR7 meant higher price and profit.
If they only new what we would pay and am paying for the car today!!!
That’s the sight. Thanks John