Accord 2003. 2.0 litre Consumes too much petrol
 

Hello guys. I bought a honda accord about 2 months ago and it is in great condition inside and out and under bonnet too. The engine and everything works similar to new. But the problem is that it drinks too much petrol. It is a 2 litre petrol car and has only done 80 000 miles with full service history. I can only go 42-45 miles per 10 liters. so it will be about 20 miles per gallon i think.
Can anyone tell me what the problem could be please?

thanks in advance!