Honda Civic Owner's Manual page 252

Fuel Economy
Minimize the use of the air
conditioning system
puts an extra load on the engine
which makes it use more fuel. Use
the fresh-air ventilation when
possible.
Plan and combine trips
Combine several short trips into
one. A warmed-up engine is more
fuel efficient than a cold one.
Calculating Fuel Economy
Measuring Techniques
Direct calculation is the
recommended source of information
about your actual fuel economy.
Using frequency of fill-ups or taking
fuel gauge readings are NOT
accurate measures of fuel economy.
Fuel economy may improve over the
first several thousand miles
(kilometers).
246
Checking Your Fuel Economy
The A/C
Miles
driven
100
Fill the fuel tank until the nozzle automatically clicks off.
1)
Reset trip counter to zero.
2)
Record the total gallons (liters) needed to refill.
3)
Follow one of the simple calculations above.
4)
Gallons
Miles per
of fuel Gallon
Liter Kilometers
L per
100 km