I had a BMW 316i a couple of years ago and a feature I liked was the economy gauge that showed you your fuel consumption at that instant. I found it really useful. Just by easing off the gas pedal a tad you could maintain the same speed but see an improvement in fuel consumption.
I've only had my i30 a couple of hours but so far I have not spotted a similar feature. Is there one?
Even though the i30 shows only an average, I find particularly after it has been recently reset that the average will go up or down fairly quickly depending on your driving...
For example if I give her a bit of a boot up a few hills she will quickly go from say 5.4 LPHK to 5.6 LPHK but then if I coast down a few hills or just cruise with a feathered throttle she soon comes back down.
I leave my trip computer on LPHK as an incentive to drive fairly economically (although I tend to drive more for enjoyment than economy these days) Which probably only makes a couple of points difference to the end result.