[i]"regardless of rolling inertia, the less weight you have, the better."
Yes, I agree ... but if your driving is mostly steady-state on a highway, you won't see much of a savings from 4-10 pounds less at the wheels (total).
And there IS a big difference between driveline mass (of course, this includes the wheels) and mass elsewhere in the vehicle. I think one car show said a single pound off the unsprung weight was worth ten elsewhere on the vehicle. Still, I think this has more to do with acceleration performance, and not steady cruising.
The best tankful I ever got from my car was 42.8mpg ... and I was moving during that interval. It was all highway miles and half the miles, my car had several hundred+ pounds extra in it ... looked like the suspension was close to bottoming out.
Get the alloys if you wish, just don't expect to see a measurable improvement.
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--- Bror Jace
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