Only 185-ish miles of actual range? Is this normal?

I know that cold weather and fast driving take more energy, as does having some heavy passengers in the car (an extra 450 pounds with their luggage, probably), but this morning my Niro said I had 280 miles of range. By the time the day was done, the battery was almost down to the turtle zone and I'd only driven about 165 miles, most of it on the highway with the aforementioned extra passengers.

Is this normal? This is my first significant highway trip with my first EV and I was not going especially slowly. We didn't use the heat much, so I don't think that was a big factor, though I'm sure it had some effect.