C5 Extremely high fuel consumption

[Szormoksegg]

Hello!

I've got a Citroen C5 V6 3.0L (2001) The problem is that my fuel economy: 18 l/100km (13 mpg) on the freeway, which I think is insanely high, because I always drive gently, obeying speed limits. I didn't notice any fuel leaks. My car recently serviced (got a new pair of oxygen sensors, changed a faulty ignition coil in the 2nd cylinder) Do you guys have any idea what's causing this?

[xantia_v6]

There is clearly something wrong, you should be getting something around 10 l/100km.

How are you measuring the fuel consumption? Is this a recent problem? What grade of fuel are you using?

[Szormoksegg]

I have filled up the tank fully (66 liters). Pumped regular gasoline into the car (95 RON containing 10% ethanol) and managed to drive only 293 km when the computer warned me about the low fuel level. I stopped to refuel, then countinued my journey. After that I had to stop again two times to refuel and spent roughly 200 EUR on gas for a 1200 km trip. Bought the car from a used car dealership, drove it only for short trips in city traffic (2-3km a day) that's why I was unable to notice it's unusual consumption.

[seanrx]

In my MK2, this happened once after refitting the battery.
I used the bsi reset procedure to fix it.
Engine sound, also return to normal.