[Paul T]

Good night to all in the i30 owners club.
My 2018 i30 CW has an occasional problem displaying the fuel tank level/ Km range . Tonight I went to visit a friend and the Km range read 534 Km approximately). When I started the car a couple of hours later the  Km range read 716Km. (With the current price of Diesel I don't think anyone is going around breaking into cars and putting fuel into them !) This has happened before twice and it rectified itself at the next start up but it is getting annoying now.
I wonder has anyone experienced the same problem? From past experience I have little faith in the Hyundai dealers here being able to fix it. (Good at selling, bad at saving).
Thank's In anticipation of a ressponse.

might not be a problem , correct me if im wrong but the klm range depends totally on how youve been driving for a while beforehand , for eg my v8 could say 700klm range then after putting my foot down a few times it will say something like 280klms even with a full tank  ..my thinking its just an average range and calculates depending on conditions

[eye30]

My range changes depend whether I'm town driving or longer nonstop eg motorway.

As example my mpg in town will show 35/38'ish mpg but if I do longer trip with hardly any stops, eg motorway/dual roads this will rise to say 44/48'ish. Sometimes higher if a longer trip.

So same as previous post.

[Greyhound]

Is it just the Range display or is the Fuel Level gauge itself varying wildly?
Calculation of Range from mpg/km.litre measurement may be affected by driving conditions, driving style, weather conditions per trip. e.g. 0mph whilst defrosting and going nowhere for some time.
I guess the Range and Average mpg calculation would also oscillate more if you have recently Reset that measurement and lost the smoothed long term Average.   

[Paul T]

Thanks for the replies folks, I understand what you are talking about and the range indicator did fluctuate a bit all the time but the problem only started last November where the range varied wildly, also the actual fuel gauge varied as well.

[Quarrion]

I've previously looked into how fuel stats are calculated on my 2015 Diesel and from my understanding it's like this:

Fuel amount: should only go down as you drive and up when you refill (duh)
Average Fuel consumption: based on all driving since last reset, regardless of refills
Range: Starts based on either Ave fuel or fuel used last cycle then adjusts based on current cycle. I've only ever had this go up when I manually reset. (or fulling up lol).

There's a few things I've done where I've noticed significant changes to the range but the most surprising was significant driving on different freeways. Same amount of freeway driving but on the other side of the city and it dropped almost 0.8L/100.

[Paul T]

Good night folks, The problem seems to have resolved itself, but there is a lot of sense in what you are all saying and it is possible that what you were saying is what was happening to me and on thinking back to when it first started, I had filled up the tank and the fuel came up into the filler pipe so maybe that upset the monitoring system, thanks again for you suggestions and help.