I filled up Mirage #2 @ 719 km / 447 miles and it came out to 64.5 MPG US = 3.68 L/100 km.
Can we call it 65?
That may be the high-water mark for this year; probably the last warm weather tank that won't include at some highway driving with the kayak sticking out the hatchback, which wrecks aero. Seems to be a 5-10% MPG hit.
But I did figure out how to remove the factory drag-reducing spoiler for future trips, because it actually makes aero worse when the hatchback is half-way open vs. none at all.