It would be interesting to hear from Vegas (and Axis) owners with newer motorhomes that have the V8 instead of V10 to see if it makes enough of a difference to stand out. Given the wide range of reported data, any possible improvement may not be possible to detect.
The newest 24.1 and 24.3 floor plans on E-350 (versus other two floor plans on E-450) may do a little better if equipped with available taller gearing, plus they are a little lighter to start with (not that weight makes as much difference at highway speeds).
I know 1 MPG or about 10% won’t make or break a trip, but saving an extra $10 or more with each fill-up is nice if there are no associated downsides.
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