The Ring Road is 1,332 kilometers. Seven days is not enough. Ten is about right. Twelve is the sweet spot.
The wind
Let's get this out of the way: the wind in Iceland is not like wind anywhere else. It will open your car door into the adjacent lane. It will take sunglasses off your face and deposit them in a different country. Rent a bigger car than you think you need.
What nobody tells you
The waterfalls are incredible. The glaciers are incredible. The moss fields are incredible. But what I remember most from Iceland is the silence.
We pulled off the road somewhere in the east, on a cliff above the ocean, and stood there for maybe ten minutes. No other cars. No birds. No wind, for once. Just a vast gray-blue nothing stretching to the horizon.
I think we paid for ten days in Iceland to find that one moment.