Help for my AYGO

Hello everyone, I’ve been driving an Aygo for about a year, but this does cause huge problems. The consumption is on average 6,2l, only on the country road and at least 30 min. driving time much too high. Also the engine power is certainly not as it should be. The motro runs again and again restless, and the performance falls partly so far, that I can not keep on the country road, at headwind, despite full throttle and shut down the speed. With this problem I have already been to my factory town several times, which told me, however, that the engine power is now like this with a 3-cylinder and the consumption data of Toyota are so literal: “Marketing washes on which one does not need to give”. I then turned to the Toyota customer service, in the hope that one would be more competent and helpful here. But also here (or would like) one can not help me. Did any of you v or even a solution ready? Many thanks in advance, I count on you.