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 just bought a 95 Honda Civic EX. Vtec with 5speed manual
transmission.

The gas gauge does not work. The previous owner told me "to be safe"
fill the tank every 200 miles. When I do this, It usually takes about
5.5 gallons.

I was wondering if other civic owners can tell me what their average
total miles per tank full they get (based on the 5speed). I drive
mostly highways @ 65mph & I usually shift at 2.5 on the tach.

I drive 100 miles everyday, and it sucks filling up every two days. I
plan on getting the gauge fixed, but with my work schedule I wont have
time for about a month.

Any input would be appreciated.

Thanks in advance,

Jesse