I reproduce this idea from the Bolt forum where some folks were complaining about the lack of a fuel gauge. The simple idea is to reset a Trip Meter (I use #1) to zero at each complete fill up. Then here's the trip mileage readout based on a 3.4 US gal fuel tank, economy of 51 mpg and the warning light coming on with 0.74 US gal remaining:
Miles Fuel
0..........F
43......3/4
87......1/2
130....1/4
136......R
173......E
Naturally, your mileage may vary....