I've never had mine beep at me, but I've had the blinking last bar twice. I don't make it a habit to do that, but I've utilized the "estimated range" in drive info to estimate how much I have left. I try not to let it get <50mi before I fill up.
The car beeps when the last bar starts flashing. If your radio is on, you can't really hear it... almost worthless, honestly. So you're saying you usually put ~ at most 7 gallons in your car at each fill up?
If it beeps mega soft, that would explain it. My hearing isn't the greatest to begin with. With gas, I usually fill up with 6-7 gal at Costco or the base, at most I've done is 8.3 (8.6?) per the gas pump meter. That time I did I was abusing the crap out of EV mode and made it a point to not let the gas get that low again.
Haha, livin' life on the super edge? May have to cautiously pass on that one. Brb, going on my spelunking and prototype parachute North Korean tour. #humblebrag