Nice find. I'm happy to see a video of someone testing at higher speeds because where I live most highway driving is 75-80mph.
Don't worry, 20 km is nothing compared to the range of the Ioniq EV, even if you drive 130 km/h in winter.I will only get my Ioniq in May, so I can't report yet. I'm really anxious to see the mileage I'll be able to get out of the car!
My 20km home-work commute currently consists of about 15 km highway and, knowing myself, I will not be able to hold back and keep the speed below 120kmh -- 130 is more likely :-D (living in Munich, Germany)