Looking for input on purchasing the most efficient car

[Buurman]

Hi there,

My name is Jan, and I'm looking at purchasing a more efficient car, but have a bit of difficulty making sense of the data. I'm currently driving a 2002 Seat Ibiza Stella, doing on average 16km/l, 90% highway. My choice to replace it has to do with the increasing maintenance cost of this car.

I've saved enough to purchase a small car (Ibiza, up!, I10, Panda etc.) from around 2012 - 2016 era. I've researched each and my goal is to optimize it to the fullest extent. E.g. reliable car, low maintenance cost, low fuel consumption. Hence, why I'm looking for advice.

How much should I focus on the statistics? Currently, Hyundai i10 would be my top pick, but the logged fuel consumption in fuelly is just sad. Is the data statistically significant, or would I be able to get over 20km/l with one?
I also see discrepancies between versions of the same car. Is it known if these differences are significant, or they can be explained by driving habit, location, and other factors?

I see very few cars optimized for fuel efficiency, here. Plenty with extras I've never had, like air conditioning and cruise control. While I would like to have these features, all come at a price, of course. I have seen tech like 'blue motion' in VW polo, promising a better fuel economy. Is it worth it to look for cars without gadgets, and with the fuel efficiency tech?

It's clear to me the 25km/l numbers listed are what manufacturers claim, and not what people do in the real world. But, what choices should I make in a car purchase to get closer to a more reasonable 20km+/l?

Thanks.