Did you ever notice that the miles to empty accelerate when you get towards 0. For instance, the MTE ticks down consistently (mile for mile) until it gets to about 10. Then, it starts to tick down 1-1/2 to 2 miles for each mile driven.
Actually, I made it about 10km after my gauge said 5km DTE and another 14km after it read *. I was really lucky to make it to a gas station (I had long given up on making it), by driving really easy on the throttle and more slowly than usual.
Also, if your engine is cold, it will be running rich, which seems to make the DTE drop FAST when it's almost empty. I guess the calculations don't take that into account.
I guess it all depends on conditions, but the calculation is just a rough guess.
Keeping the tank somewhat full is good for a couple reasons. Keeps the pump cool. Keeps from sucking up any crap in the tank - or at least a better chance of not.
I agree completely, but in this case I was on a long trip, and several gas stations I passed had no fuel, and then I ended up on a road that I didn't know that turned out to have no stations at all! Talk about stress.