When I was test driving our first Ioniq, the one before our previous one I was already sold to the car, but what impressed me the most was the small details in usability.
One such thing was the side mirrors which would turn slightly downwards when you put the gear in reverse to allow better view to where it matters. I don't know if any other automaker has this feature nowadays, at least I haven't seen or heard if they do.
It wasn't a ground breaking innovation or huge improvement for overall usability of the car. But it assured me that the designers were actually caring about such things. It wasn't even advertised anywhere, you couldn't find a mention of that in the long list of features.
In the new car this is not an option anymore due to there not being any side mirrors. But the cameras replacing the side mirrors offer another, even better feature: wide angle view!
The mirror/camera thing wasn't what impressed me this time the most. The small detail added in this one, and the one I only realized few days ago is the little automation that turns the internal air circulation on momentarily when you apply the wiper fluid to wash the windshield to prevent the smell of the cleaning liquid carrying inside.