I've only gotten over 300 miles on 13.5 gallons about a half-dozen times, but it was on Shell gasoline, and 93 octane or the VPower whatever stuff, once, and that was on the 1st leg of a multi-stop, 427 mile trip, from Oakland Township to Traverse City, Michigan (from time of 13.5 fill on empty, to maybe 8-10 miles from time low fuel light came on, I had traveled 304 miles, an all-time best).

Like I said, my average 13.5 gallon fill lasts 270-280 miles, and there a lot of idiosyncratic things about my 8, including the roughly 75,000 mile spark plug/coil packs change interval.

My 8 is unique; I barely put more maintenance into it (exception of keeping oil at full mark and good coolant system care) than the typical plain vanilla daily commuters I've had, and I'm on original motor at nearly 160,000 miles from time that vehicle was purchased new by me, and I've had no problems other than 3 recalls and a starter motor/battery replaced under TSB for free, and a code Brown at 78,000 miles which my first replacement of spark plugs/coil'packs resolved.

It's freaking hilarious.