Why my honda civis 2006 hybrid gives me only 31 miles per gallon. i did full service everything. is there any solution to increase the milage

the only true way to check fuel economy is to fill tank drive till 1/4 full do this 10 times taking your milage reading before each refill
that will give you your average milage
now if you live in a hilly area and your up and down all the time that will also throw all stuff out the window and in order to get what the manufacturer suggests vehicle will do for avg milage is to go at a steady 30mph on a very slight banked oval tack that is basically flat That is how manufacturers of vehicles get the milage a vehicle will go per gallon

One tank of gas is not enough to compare mileage. Or are you saying the computer's readout of mpg estimate is showing less? Try a tank or two of premium and see if that helps. Keep track of gas mileage. Driving techniques have a lot to do with gas mileage, as does long trips vs. short trips, highway cruising vs. city driving. For best mileage, do regular maintenance and keep the car in top running condition-good spark plugs and clean filters and clean oil ! Attend to minor problems before they escalate.
If you want to check actual miles per gallon, start with a full tank. Write the odometer reading down, and go. Everytime you put gas in, write down the amount. When you are close to 1,000 miles from the time you started, go fill the tank and include that amount of gas to your previous list. Now add up all the gas used and divide it into the miles to get miles per gallon. (976 miles/31.8 gallons = 30.69 mpg ) . Only one tank will skew your numbers, might be off cause the tank was filled more to the top than the previous fill-up. About a thousand miles of driving will give you a very accurate figure of miles per gallon for your car.

Personally i donot think you need to put the four point plugs in your car.That would just increase your fuel consumption a bit as it would be burning more fuel to give u the advance pickup.You really donot need that.Put single point Champion plugs,they are really good.Then Bosch, Denso or NGK come in line.get the distributor rotor clean so that strong current goes to the plugs and its all set.On average the SUVs the size of your car would give 7kms on a litre petrol in an average traffic city drive with Air conditioner switched on.You can convert that into milage per gallon.Milage generally increaes by 25-30% without the airconditioner.

there is a book publish by the govnt or minister of transport on the exact milage as well if you know how many liters or gallons go in your tank like 80 liters and the gas is 1.00 a liter it cost $80 for 80 liters on a full tank you do 500 km but make sure proper conditions of 100km a hour tires all proper equal pressure the wind is also a facture there is a lot involved to calculate your gas proformance as well if you had a oil change done latly you can find out on a govt site for gas consuption or consumers report

it sounds more like that old adage....how long is the piece of string.... i don't think you can ever predict if something will last longer than others, you might buy the hybrid and drive off the forecourt only to have it brake down 2 miles up the road, and vice versa with the normal civic,or they could be looking at 10000000 miles.. they are to be honest just as good as each other, obviously the hybrid is better for the environment and cheaper running cost, but just as all honda's they are both very reliable, i truly think you should toss that coin of fate and see what side it lands, either way your a winner..hope this helps...sorta lol

Take it to a autozone and have them pull the codes and tell you what is happening, it is most likely a 02 sensor not functioning properly. But have the codes pulled right away, andthey can tell you what it might be then post the codes here then we can tell you if you should wait or not. better safe than sorry. If you drive it and it brakes and you knew the light was on and di not get it checked right away you could void the warrenty.

Do you normally accelerate quickly from stopped? You can increase your cars mileage by cutting down on rapid starts and stops. A comparable Honda Accord Hybrid rated at a higher 25city 37 hwy MPG rating achieves less than 22mpg when driven HARD

First things I would look at is,did they put 10w30 oil in and not 5w20 or 0w20,it makes a difference in mileage (if they run out of the correct viscosity oil they WILL put in what they have).
Did the service include a spark plug change?Is the spark plug gap correct?
Did they do a brake service?Is a brake dragging,a little to tight?Did they clean the throttle body?Maybe the engine was running a little lean before and now is at the proper fuel mixture,with less MPGs but running clean at the exhaust.
Weather conditions?Head winds and colder temps reduce MPG.

Wide tires make less gas millage, get narrow wheels, let the car accomplish speed slowly from 0 to 30, look at air filter,if shortly replaced, oxygen censor, 15 miles is normal 16 miles per gallon is good for a V8

A hybrid vehicle is a vehicle that uses two or more distinct power sources to move the vehicle.[1] The term most commonly refers to hybrid electric vehicles (HEVs), which combine an internal combustion engine and one or more electric motors.