What if..;.

Cool pic, but I can't say I  would want one. Too much T-bird in the design. And I didn't care much for the T-birds of that time frame. Thanks for the cool pic though John. I still dig seeing this kind of stuff.😊

Yep, Geno speaks for me too.  

It's nice but it's just another run-of-the-mill 4-door hard tops.

If I thought it would have saved the Mercury from extinction I would be in favor of it but I doubt that it would have happened.

I have such a very positive feeling for the original Cougar design that I can't give this design fair consideration.  It would be great to see various angles of this design all the same.

I think it’s a handsome design but why compete with Thunderbird? Also, to me, rear seat access appears a bit tight due to roofline design so watch yourself. 
I happen to really like the 67-69 T-Bird desigh. 
Steve

If the tire sizes were the same, front to rear, the nose lowered so the body was parallel with the ground and the top moved back about eleven inches, to where the inside roof line came down at the rear door's rear seam, it might have worked.  As it sits, no one would want to go through the gyrations necessary to ride in the back seat.  The Cougar original was long in the hood and short in the trunk and the 4-door would need the same appearance to be considered 'one of the family.'  Interesting suggestion, though JK.

I could run it through PhotoShop to illustrate the suggested changes, if it's of any interest.

@gdh I believe the rear door would open just in front of the carriage roof molding similar to the 4-door Thunderbirds giving amply room to enter the rear seat. Just a guess on my part. 
I wouldn’t be interested in a 4-door Cougar. It looks way too long and looses its “cat” status.

It is a very interesting design and rather cool as long as Mercury also made the 2-door coupe also. This Mercury automobile would be Steve McGarette 5-0 ride for sure !

The lines show the door seams are laid out in this manner, which would make for an uncomfortable ingress and/or egress to/from the rear of this car.  The lines show up better in PS.

Here is one of my notoriously quick and dirty Photoshop efforts, extending the roof to give more of a long hood-short tail look, but I don't think it helps much. Still a fairly clumsy and unimaginative T-Bird clone and I don't think it would have done Mercury much good.

Actually, my image could give the illusion of it being a six-light design, rather than a heavy T-Bird rear pillar treatment, which might have made it interesting. Or not.

@gdh

that could also be the molding separating the vinyl from the body on the door sail panel. 

@100ford2003 On the four door Thunderbirds, part of the vinyl top panel opens with the rear doors making entry and exit easier.

I think everyone makes good points here, and I agree. It's interesting but underwhelming. I'm not sure there would have been a market for this version. Apparently, so did the folks at Mercury.