The interior was definitely a cut above a comparable Mustang, Camaro or Firebird, this was back when FoMoCo actually understood what Mercury was supposed to represent. A top of the line XR7-G (that's the later Dan Gurney Special that was way more than just cosmetic) with 428, factory sunroof and leather interior has been on my bucket list for a long time. I'm not sure whether it looks better in black over black or in the very popular Lime Frost of the period, either way it's a beautiful car and underappreciated from a design standpoint.
This one in the photo is very nice but the wheels are buffed out and not sure I like it better than factory with dark matte coves, and those white letter tires haven't aged well to my eyes, honestly I'd probably prefer some Silvertown redlines on there. If I could get my hands on the Rader aluminum rims originally intended for the car, that would really rock, but they're hard to come by. Sort of resemble Fikse FM10's in a way, they're especially fetching on a black car.
Here's a nice little link on the history of the XR7-G, you'll have to cut and paste into the browser address field, it's late, I'm lazy so the hyperlink isn't active:
http://www.fordmercurycougarxr7.com/pages/History/CougarXR7-G.html