This is something we've been keep tabs on since replacing a few of the suspension components and new steering components on our jeep. I'd have to say before 20K miles the jeep was getting around 20 City 24 highway. Since adding these new products to our Wrangler, we're getting in the 17's highway. However a few weeks back I noticed a significant drop in MPG when the front drag link, steering damper, tie rod end links were damaged while driving over a pot hole. Our MPG dropped to 15.2. We've since corrected this with a re-alignment and the MPG is back up to 18.9 This is on the 16'' factory steel wheels & 31'' dueler tires.. prob one of the worse combinations. Most tire charts seem to indicate that with an upgraded tire wheel combination, we'll be able to achieve better MPG in the future. looking to see maybe a 2% increase in the MPG after the new wheels and tires have been mounted. I look forward to reporting back with these results afterward.
Semi-Retired Sr. Mechanical Assembler & Sr. Quality Assurance Inspector for Aerospace Industry