Fuel consumption

I have 1998 model 1.6 306 friends, I have 35-40 cents more on the long way between 50 cents in the city.
I also use the vehicle at normal speed
If not, what would you suggest me to do?
Thanks :)

If there is no LPG, according to these prices, it is normal for me

I think it's pretty normal. Gasoline 6 tl already.