Just bought a 2000 X reg V40

[T5 BOY]

Hi all,
i've just bought a 2000 Xreg V40 1.8xs for £1800. It has full history with 72000 miles on it and is in imaculate condition. I have had to buy it as my 850 T5 cd has died.....
I have been on some sites and they are saying that as the V40's gain the mileage you can have engine problems unless you use higher octane fuel. I would like to know if anyone can tell me what these problems are and if i do have to use the more expensive fuel. I do love the car even though not as fast as the T5 but if i have to use the different fuel then i will consider getting rid.. I also have read on one site that they had to have their engine decoked, i thought decoking was a thing of the past....
Hope someone can shed some light on this.

[-CHRIS-]

Depends if it is a 1.8 or a 1.8i. The 1.8i is a GDI mitusbishi engine which is what you have been reading horror stories about.