What is the cause of excess fuel consumption on a Daewoo Nubira 2001?

what is the cause of excess fuel consumption on a Daewoo Nubira 2001?|||Being a poorly made automobile? Seriously though, it has several reacalls on it, so maybe thats the problem...|||old oil out of tune engine bad tires|||have you hooked a OBDII code reader to the vehicle? try giving it a tune up. new air filter, etc.