uh, no.......The unsprung weight difference in a passenger car is virtually non-existent. Now if you replace the wheels with aluminum ones and make them real skinny with real skinny tires....yes, that would reduce the unsprung weoight and if you jacked up the pressure to 55 or 60 PSI additionally.....THEN you would see a mileage difference. In that scenario though the real mileage difference would come from skinny, high inflation tires and again almost nothing to do with unsprung weight.

Unsprung weight is factor in handling. Reducing the unsprung weight to increase mileage would be like lowering the roll center or changing the polar moment of inertia to get better mileage.

Spaw