Ok, so according to my research the ecoboost can use e10 fuel, whilst the GT has to have the 98 RON.
Just going through the owners manual for mine (GT) and it states (pge 98):
"We recommend that you only use high quality fuel the car."
"The engine in your vehicle has been optimised for operation using 95 octane unleaded gasoline
"The engine in your vehicle can also operate using 91 octane unleaded gasoline. However, if you choose to do so, you may notice some minor loss of performance, economy and increase engine noise.
Your vehicle is suitable for use with ethanol blends up to 10% (E5 or E10).....the use of gasoline containing ethanol may increase the fuel consumption of your vehicle."
So, it would seem that it can run on any of the 4 petrols on offer - with noted loss of power, performance and increased engine noise for the 91 and E10.
Whilst I wouldn't love to use nothing but 98, I have to be practical in the knowledge I'll do 40,000ks a year in mine as she is my daily drive. So thinking of going with the 95.
Thoughts?