Hello i am from europe too, but from small country named Slovenia. In our country you can not have tires that are not written in homologation. You can not change something in your car, without enter the changes to homologation and you must pay aprox 50$ for everything that you change on you vehicle.
So i can not have 15" tires on my suba, because in homologation are written only 13". If the police stop you on the road and you do not have changes writen in hmologation, they could take registration plate from your car and you must not drive with it until all the changes are written to homologation.
But the gas in our country has 95 or 98 octans, the price fo 1 liter is 1.06$, that means that for a gallon you will pay approx 4$.
But the water pump cost me 77$ and the whole car Subaru GL 4WD y85 cost me 103$.