I agree - 6.8L is "only" 415 cubic inches. Certainly not huge when one remembers that 350 used to be ubiquitous in anything bigger than a subcompact car. GM's 454 V8 was a fine engine and when I had one in a 22 ft Class C it got the same mileage or worse than my current Ford. It's gonna take a fair amount of fuel to make upwards of 100 hp which is what my scan gauge says it takes at cruising speed.
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