I gotta figure that saving 1lb or so per wheel is a waste on the open road (limited-access highways). Yes, it takes less energy to get a lighter body of mass up to speed, but once up to speed, it takes little energy to keep it at that speed ... a body in motion tends to stay in motion.
It's hard to believe, but supertankers are very, very efficient at moving bulky cargo, probably for the same reason.
My Dad manages real estate. I remember him telling me that when working with freezer/cooler buildings, it was cheaper to run them when they were full rather than empty. It's thermal energy instead of momentum ... but hopefully it helps illustrate the principle here.
Short answer: skip the alloys unless you are into bling-bling and get some smooth wheel covers instead.
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--- Bror Jace
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