You have room to go and gain even better mileage.. Actually my QC on a long haul from a Tampa to SC and then Va. years ago I got I think tops was 15.4 driving trying to squeeze out the best mileage… the base line range avg. is from 13.8 to 14.4 ….
Usually staying under 70 was the best mileage speed range ..
the last time I went to SC .. on the way home I noticed a slight misfire and a ticking noise thinking it was something going bad in the valve train .. it turned out after checking the codes and showing several cylinders saying misfires . Well it actually was a bent plug electrode on the rear passenger cylinder.. I had those plug in for about 2 years and the only problem I did notice was my mileage had dropped after installed to around 12.8 .. ran fine no noises .. no problems until that trip .. I was thinking the worst that the plug had possibly hit the piston … well contacted Stinker about rebuilding and new engines ? Decided to just try a new plug and guess what ,, fixed the mileage and no noises and has been fine for years .. my guess is when I installed the plug I must have bent the electrode slightly and over time it must have worn and bent more due to the combustion pressures ..
