I'll be Ralph's counterpoint. I have a loaded 06 Mustang GT and I've driven my Parents 08 Sable Premier a couple times.
Mustang:
The Ride can suck on it at times (uneven roads), but its a vast improvement over the 98 Mustang GT I had and was almost on par with the 02 SVT Focus I had. I drive the car every day and have a tad over 50K on it
The plastic interior kinda blows on it, but this looks to be fixed on 2010MY. I love the design, but the materials leave alot to be desired.
Zero problems with the Mustang since I got it, though I've had two gremlins with it...check engine light came on when I first got it and then went off, and I was having issues with the driver sides window not seating properly the past couple weeks...but has been fine this week. Go figure
Sable:
Has decent power out of it with the 3.5L
I'm underwhelmed totally by the interior...even though it has soft touch plastics, its pretty lame designwise. I don't like the command seating on the car, I feel like I sit up way too high in the car..
Handles alright for a car of its size.
Overall I'm bored to death by the Sable, but I'm pretty excited about the new Taurus. it fixes the styling issues inside and out and looks to be exciting