FYI the dash reads 3.9 Miles/kWh, which with 21kWh capacity indicates 81 or 65 miles range. It seems optimistic to me. My wife took a 52 mile journey last weekend, left with approx 90% charge, which according to the dash would yield 71 miles. She got home after consuming part of the second bar, I don't believe she could have got another 19 miles out of the vehicle.
Honestly, if you're trying to correlate the dash "guess" with reality, you're just wasting your time. That 71 miles number you saw could have been 100 miles just as easily on the Guess-O-Meter. I recommend not using it at all.
Yes, your 3.9 miles/kWh (from the dash gauge) will, in fact, take you that 81 miles, if, and only if, the terrain if mostly flat, no significant heat or cooling, no elevation changes, etc.
She absolutely could have gotten 19 more miles out of that car, and when there was only one bar remaining, about 15 miles, and then about 12 miles when the first Low Battery Warning came on, and then about 5 miles when Very Low Battery comes on.
Again, within the context stated above. I've reproduced those numbers with my car many, many times.