Did you know ?

[FL SAAC]

Many know that the 2006 Shelby GT-H received a horsepower boost over the standard Mustang GT. The bump was the product of a cold air kit along with unique engine calibration. Those changes also necessitated that the GT-H would require premium fuel.

By July 2006 (the first 20 GT-H models were produced the week of 4/17-4/21) Hertz started reporting to Ford Racing that the GT-H was experiencing limited engine issues.

Ford Racing determined that the GT-H was suffering from "excessive rental abuse and octane lower (fuel) than that required."
By late August 2006, Ford Racing explained to Hertz that it wasn't reasonable that customers would use premium fuel, let alone return their rented GT-H fuel tanks full with premium fuel.

Ford Racing concluded that the best course of action was to quarantine each GT-H in the wild and install a new engine calibration, which would allow the GT-H to run on regular fuel. The only drawback was that the Shelby GT-H would now produce less horsepower than originally desired.

So there's a unique piece of unwritten Shelby GT-H history

[ChicagoChris]

Very cool bit of info. 
So unless the post-Hertz owner of a 2006 GT-H recalibrates the engine, it has less HP than the 07-08?

[98SVT - was 06GT]

I'm surprised the ECU didn't compensate enough for lower fuel grade.
I wonder if there is a back story that the recalibration wasn't certified by the EPA.