[KevinW]

So my car was brimmed for its IVA test (the extensive Uk test needed to get a car registered). Apart from being tested on the rollers for speedometer and brake tests and revved a few times at different points during the test, it has now done a 20 mile round trip. I have now topped up the tank and estimate i have averaged 6 mpg!

This is a 428 (not bored out), no big lumpy cam, achieved around 480 hp on the dyno, similar in torque before installation, 4 speed toploader and a 2.88 diff and was driven really very gently during the summer when it was hot here (95 degree F - that's UK hot).

Running rich? I thought i would get 12mpg easy. As the OP said, mpg and FE in the same sentence is a joke, but with much higher price of fuel in the UK, i am a bit disappointed.