pretty sure it has an 11 gallon tank, so you are filling at 1/2.  Means you
could get around 400mi, no??

The owners' manual for your Honda is free online at a few
sites. Most likely you have the Civic with an 11.9 gallon
fuel tank capacity.  From fueleconomy.gov, I figure a
conservative estimate of your mpg is 30. A speed of 65 mph
is a good, fuel efficient one for highway driving. But
optimal efficiency probably occurs closer to 50 mph. Also,
condition of the engine can affect mpg a lot. E.g. are spark
plugs and wires replaced per the owners' manual's
maintenance schedule, using OEM recommended ones? Do you put
a bottle of the fuel system cleaner "Chevron" Techron into
the fuel tank and thus through the fuel system every year or
so? Checked the PCV valve recently for operation and
cleanliness. It's likely due for replacement, so as to err
on the safe side. It's cheap enough.

Remember also that some conventional wisdom suggests not
driving until the fuel tank is too low, since it's said that
debris accumulates at the bottom and is more likely to get
sucked into the fuel system (filter, etc.) at low levels.

I concur that filling every 300 miles should be safe.

But "YMMV." So monitor closely.

   I have a '95 EX Sedan 5 speed that I've been driving since early
Summer. I average 35-41 mpg in driving that is about 3/4 highway, 1/4
city. The precious owner, who I assume spent some time in stopped
traffic, averaged about 32. If you are driving a hatchback you probably
have a different engine (mine is the 1.6 VTEC) and may get different
results. My gas guage is also off: it reads about 1/4 tank too low. I
feel comfortable going 300 miles between fillups.

   BTW, do you find that your car is geared too high, that the jump
from secong to third is way too large...?

-------------------------

Please explain: "The gas gauge does not work". Maybe we can help you
solve that too. It comes up from time to time.

'Curly'