Quote:
Originally Posted by chrisl
I still think that my favorite of the GM OHV engines is the LS7 - high revving, naturally aspirated, and tons of torque at all RPMs.
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Yeah, and that definitely helped it get pretty decent highway mpg too. Which brings me to my question...
AMG's 6.2-liter was just a hair less torquey given the slight displacement deficit but even in its M156 tunes (rather than the M159 tune in the SLS AMG, which isn't really a fair comparison), it still matched or beat its hp and torque numbers in most applications above the standard C63. How come its highway mpg was so poor in comparison? I'd assume that the car had enough bottom torque to keep the car moving at highway speeds without needing too many revs (like the LS7 or even the LS3, which was also a 6.2), yet its gearing wasn't really as tall as it could've been, especially with a seven-speed transmission.