I put E Flex petrol in my XV car by mistake. Is this really bad for it? Can I run it for a tank of petrol or do I need to get it taken out?

running one tank should be no problem. the biggest issue with that fuel is that it has a higher amount of ethanol which eats away the rubber hosing. i am not familiar with the hosing they used in the 2012 cars but one tank shouldnt cause any major issues. there may be some sort of additive you can add like injector cleaner or something that could reduce the issues but i am not positive on that. basically shouldnt be an issue but don't push it and use a bunch.... i would also fill the tank up with premium when its half full to mix it up a little to reduce the potency and do this a couple times at only a half or quarter tank low this could help