Bro if ur civic is prosmatec then maintain its RPM around 1.8- 2.0 k. and use very decent light foot while accelerating. maintain a balanced distance from cars infront and use minimum brakes it will save a lot of fuel.
If u r driving manual transmission then you can control fuel with light foot acceleration, change gears maximum arround 2.0 - 2.5k RPM try to drive in 5th gear most, Do not down shift if not needed.
Like i drive in fifth gear mostly maximum at 65 KMPH shift 5th gear. i drive @ 85-95 KMPH, and if i need to use brakes, keep the distance from next car. when u will leave accelerator it will automatically come down slowly so u will save brake pads, fuel....