I drove several 5.0s when i was looking to buy a new mustang and i think i discovered a few of the reasons why people either felt underwhelmed, or that the car was souless, or wasnt as impressive as they had hoped.
I test drove the following vehicles:
2013 Green GT Automatic
2013 Green v6 Automatic
2012 Red and White GT Automatic
2014 Silver GT Automatic
I prefer automatics due to a past wrist injury to my right hand, tho coincidentally i bought a manual because i simply couldnt walk away from the deal i got.
Anyway, car 1 had good takeoff, but seemed to not top out, then i realized the sales guy had slipped the shifter to 2, thus limiting my speed. I pushed it up to D and he pulled it back to 2 and said "we need to leave this here". I replied, "then i need to leave this here with you", and we went back to the dealership and i left.
Car 2 was as to be expected, the sales guy spewed numbers from the brochure about power, but i think my 96 GT could have roasted it off the line, just by the feeling of it.
Car 3 was either a little different from Car 1, or i missed on noticing something on the shifter, the Sport Setting. Turned that on and told the sales guy i wasnt buying without testing, this sales guy aparently wasnt a puss like the other one, and just held on. WOW what a difference that little setting makes. 95 by the bottom of the short onramp, and before i even realized it we had passed 5 exits. Hammering into the gas at any speed it pulled like a rocket no matter where the RPM was. Completely different experience.
Car 4 was a repeat pretty much of Car 3 but this one felt a little lighter on steering which was nice. With the sport mode on, it was like driving Car 3, with upgrading steering.
Car 1 just wasnt like the others, i dont recall it having the sport option on the shifter, and no matter what i did, with the shifter where it was it would never come out of 2nd, so driving back to the dealership doing like 50 on the surface street at 4000 RPM as it refused to go to third, and the sales jerk made me leave the shifter alone.
I ended up getting a deal on a 2007 GT Deluxe, with a full shelby style paintjob and lots of extras and upgrades for less than half the cost of a 2011+ so i took that one and ive loved it ever since, a manual with 3.55 gears, aluminum driveshaft, and 255/50/R17s Takeoff is awsome.