Maybe there is something wrong with my fuel sender because I usually get between 8.5 and 9 liters per 100 kilometers (26 - 28 miles per US gallon) and fuel gauge is less than 1/4 past 200 miles. Theoretically I should get over 300 miles per tank too !
Your float arm needs calibrating.
Ideally the arm would be set so that the low fuel light comes on with around 2 gallons left in the tank. (IIRC 'reserve', ie: when the light comes on, is 1.3~1.5, but 2 is safer)
With an empty tank, pull the sender, put 2 gallons of fuel in and with a few trial and error attempts, adjust the float arm (bend it) so that the low fuel light
just comes on. if you can get it to flicker, even better yet.
On solid with a bit of flicker if you give the car a little jounce is also acceptable.
Button everything up, and from that point on, when the light comes on you'll know exactly how much you've got before you're walking.
Nevermind where the needle falls when full if it spikes way over or just short of the gauge full mark. You know its full, and a full tank of gas usually won't leave you stranded. Approaching empty on the other hand is real important to know about.
AFA the original topic:
An L-jet in stock trim and decent tune should see you reliably getting at least 300 miles per tankful (25~ish mpg) and likely more than that as the 30+mpg stories are definitely the more prevalent average. (I vaguely recall window stickers or adverts mabe saying something like 27 city, 32 highway)
IMO, 300 should be the minimum acceptable before seeking out the reason(s) why the mileage has gone to crap.
'Course if you're dealing with a tweaked engine, then be happy if you see even 20mpg.
