I have 2.4 liter Audi A6 car gasoline. The consumption now is 25 liters per 100 Km which is too much, it must be 15.4 liters per 100 km How can I solve this problem?

it would be blowing black smoke and running very sluggishly
for starters run the fault codes and fix the faulty sensors
check for a failed cat converter blocking the exhaust
consumption is calculated in liters per 100 KM
check that you do not have it in 4 wd on hard surface roads as that will seriously affect consumption

Problem with my Ford Ikon 1.6? ' Yahoo Answers

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Jun 10, 2012 - The same problem presist on slow speed also. ... Still the problem presist on sudden acceleration and when we strart up in signals. .... Ford ikon 2002 clx 1.6i starting problems start quick on running can it be the starter?

Ford Ikon fuel consumption, miles per gallon or litres/ km ...

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Ford Ikon fuel consumption, miles per gallon or litres/ km ... How much fuelconsumed Ford Ikon 1.6 i, liters / 100 km or miles per gallon. Ford Ikon 1.6i it is a ...

Hi Faisal
The only way to find the problem on your Audi is with genuine Audi diagnostics software if you have a defective oxygen sensor it will put your engine management light on.

Likely, it could be the O2 sensor, stuck or debris in an injector, or weak spark. Fuel pressure tests will point you in the right direction

driving in over drive mode actually is what gives the economy as the engine rpms will be around 300 less than direct drive . Lower rpms = fuel savings
OD should come in around 60 klm/hr and drop out at around 50 klm/hr. When you are accelerating hold the pedal in a set position and watch the rev counter (rpms ) and each gear change you will see the rpms drop and then build back up as the vehicle speed increases At 100klm/hr the revs should be around 3200 rpms or less but if over ( say 3500 rpms) then may be the OD is not coming in. One way to test a box operation is to find a speed shop with a dynomometer and test the gear selections against loads and engine rpms

Driving in overdrive, say on a trip where your speeds are over 65 to 70..Actually saves gas, but using overdrive to drive around town not only uses more gas, but can cause damage to your transmission.

double posted, back up , one.

Fuel injector are worn out they. Might be dribbling as a bigger engine it won't stall or flood it raises the idling making you feel it's power but consuming more fuel

Don't know the USA system but here in Europe the sister car with the same engine does 13 liters per 100 km on city, 9 l / 100 km on road and 12 l / 100 km on highway.

change o2 sensors every 60,000 miles and use iridium plugs they will outlast engine.
check engine light will not come on until sensors are completely shot,this also goes for your mass air flow,had same issues with 99 beetle happened at 80,000 miles,changed all three items ended up with 35mpg after getting 24mpg before fix.parts are cheap on ebay.