If the display says that I have a range of X miles but Waze says that the destination is X+15 do I need to worry or is there wiggle-room?

TIA

 

When the fuel light comes on you have about 10L of petrol left. Not all can be used as the fuel is not level in the tank during inclines.

estimated miles are not very accurate.

 

Low Fuel lights and Range Displays are routinely pessimistic, they are going to warn you long before
you are really in danger of coasting to a stop. When under warrantee coverage it will cost them money
to come rescue you and regardless of cost it makes them look bad when a Lexus is stranded on the road.

Years ago when I first got a cell phone I was driving the new for 1988 Chevrolet Beretta. Had a nice safe
commute route and played with the low fuel warning. Light came on, weaved the car left and right to see
the fuel gauge wiggle. Drove another week - 60 miles. Light still on of course, no more wiggle from the gauge.
A couple of additional miles and I had to make an extended drive. Time to fill up. Full to the neck was about
2 gallons shy of published tank capacity.

 

I understand it is not a good idea to let the fuel tank run low. The fuel in the tank also functions as a coolant for the fuel pump. When fuel level is low, pump operating temperature rises, which reduces its life.

 

Both the low fuel light and the estimated range are conservative. I calculate my range when the low fuel light comes on based on my average mpg, which is usually about 2 mpg less than what the car indicates. It is 70-90 miles on my 2016 300H that gets an average of 31 mpg. I don't pay attention to the estimated range.

I think X+15 would be safe.

Your mileage may vary.