Finally filled up again in my '91 CRX HF, I drove 423.5 miles on the last tank. I could have went probably another 150 miles, but it's hard to keep going when you want to check your average all the time.
Anyway, I drove 423.5 miles on 6.525 gallons =
64.9 MPG I did the math, and thought, "that can't be right"... so I squeezed the pump again and it was full. It stopped on 6.679, which made it slightly less, so that's what I added to my fuel log.