[Francois]

Got a 2013 1.8 petrol i30 recently and everything was fine the first few fill ups, but now after filling up it is showing 490 kms left, before I was getting 530ish.
I am wondering if the i30 can detect what RON rating/strength the fuel in it is, as this time and last time, I put 95 in it instead of 91.
On the other side of things I'm worried perhaps I've ruined the accuracy by over filling, I prefer to fill up to the next $ amount to avoid getting extra coins in the change that I then have to bin. I know the manual says to stop at the first click but other cars never developed an issue because of my coin dodging habit. an extra ~50c~ (australian) of fuel shouldn't hurt to be honest.

[FatBoy]

Welcome to the club, Francois!!

The distance to empty (DTE) is a guide to how far you have to go on your current fuel usage.  If you have just filled up on the highway, then the DTE will be greater than if you fill up in the city.  There have been other posts on the forum about how it is calculated.

I don't think that you have ruined the DTE by over filling.  Have a search on the forum about "brimming" the tank to get a more accurate fuel usage.  Many forum members "brim" the tank each time they fill, without damaging the trip computers.

[The Gonz]

I don't believe it adjusts fuel range based on any detection of RON, although I think it may remember your previous performance and adjust expected range based on that particular driving history. You could try disconnecting the battery for 10 minutes to zero the computations and see what you get from now on.

PS: 

[tw2005]

It's only an estimate   and it will adjust itself either up or down as you drive.

I have the CRDi and often it shows around 740 -750 full. I overfill and I have gotten over 1000km from a tank which I think could be closer to 60L to the brim rather than the 53L. That's straight highway non stop except for breaks.

The range to empty can drop quickly too especially around town as it gets close to empty.

If you want real figures you's need to keep a log and fill up to the same point each time if you want to see how it's performing .