Join Date: Feb 2007
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The best way to measure your mpg is to fill the tank to the brim - set the trip meter to zero. At the next fill note exactly how many litres it takes to refill the tank back up to the brim. Take a note of the miles recorded on the trip meter. That way you should have a fairly accurate set of figures on which to calculate your mpg. See the link below for an online mpg calculator.
A dirty air filter and poor spark plugs will affect mpg and unless you can find out if these were changed it may be prudent to have them checked.
I take it you have done all the other checks such as sticking brakes and correct tyre pressures, etc.
Currently in madnoel10's garage:
Honda Civic 1.4l