There's a few factors that can distort that. If you were driving aggressively for most of the tank. The refuel light will come on sooner based on your higher fuel consumption rate dropping you to zero quicker with more fuel in the tank again based on fuel consumption rate. Then you baby it and fuel consumption improves leaving you more reserve. If that makes any sense. That's how it was in my case any way. If you drive soft with a higher MPG estimate all the way to 0, then drive aggressively after zero, you will probably have less fuel since the computer assumes you will get XX milage based on previous driving habits for that tank. Not sure I explained that the best.
My Brother works the highways and runs into stalled motorists all the time because they're relying on that
"estimated before empty" mileage. I've run out of fuel exactly twice in my life and both were on the motorcycle, after it sat for two/three weeks. It has a light, not a gauge, and I always fill by trip-meter. Unlike our cars, it has a vented tank. So over the weeks of sitting, I figure it lost enough fuel to evaporation to significantly impact the amount miles I can run before refill. After that second time, I don't mess around and always refueled within ten miles of that fuel light activating.
