My tank runs that way also....apparently more gallons fit in the first half of the tank ()....
oh, and it's capacity is 22.5 gallons....cuz ya know that extra half gallon can getcha a few more miles
I've gone as low as the needle can go, (but no light) and total fill was only 18.80 gallons.and 297 total miles.....
I've never hit a 300+ miles tank yet....cuz I think it's really close to empty and don't want to run out....but it appears I've got about 50+ miles left (3.7 gallons @ 15 MPG).
But living out in the boonies, and often driving off road in the boonies...that hidden 3 gallons is a great safety cushion.
OCTANE- several past discussions about Octane vs. MPG.
Some say higher octane gets higher MPG.
Someone ran a real detailed experiment on this. Can't recall who...(maybe HiredGoon??)
Think they found higher Octane (Premium) DID increase MPG a bit.
I tried it...3-4 months Premium vs. many months regular....not much difference in MPG that I could see.