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Originally Posted by f5fstop
Have to understand why a larger engine can obtain better fuel mileage.
To obtain a set speed, you don't have to give it as much fuel. True, you are actually using fuel in three more cylinders, but are you using as much to move the mass off the line.
Highway driving, now you are using five cylinders at all time. With an AFM V8, on the highway, you will only be using 4-cylinders. Good case is the Escalade that went to a bigger engine and is obtaining better fuel. Part of that IS due to the six speed trans and the gearing, but part is due to the AFM system used on the engine.
As for EPA, remember, 2008 ushers in the new ratings, so the V8 will appear to get worse, while a I-5 will also appear to obtain worse milage than the 2007.
Time will tell if it gets better mileage, the same mileage or a few miles per gallon less.
Time will tell if there is a V8, and then we get to see how GM Marketing markets the vehicle to the public.
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I see the point about the possibility of a marginal improvement in highway only mileage with a V8. But the AWD Escalade probably running premium gets 13/19 EPA mpg vs. H3 3.5 16/19 EPA mpg (comparing apples to apples). so the possibility looks somewhat bleak. Of course the Escalade is heavier but it's much more aero, running street tires, tall gearing, etc.
I'm sure GM is trying to figure what (if any) incremental sales volume increase would result from a V8 option since this really is a business decision. But I would like to hope...