First, when the "M" miles-to-empty reading went from 10 to three bars (---), it went 32 miles to MECO and the OBC mpg reading at 33, I figured there was about 1 gallon of gas left at "---"
Second, the OBC's odometer read 446 miles at MECO. As it's actually 4.5% low, the actual mileage was 466 miles. And the gauge needle was about 1/16th inch below the left-most "E" mark. There may have been a quart or so of gas left that the pick-up tube couldn't quite get to.
Third, putting in 2 gallons raised the gauge needle to 2/3rds up on the orange 'low-fuel" marker. At start-up, the M reading was 52 miles.
Fourth, I drove 9 miles to a gas station, then filled it up to nozzle auto-shutoff; it took 12.4 gallons. I calculated there was 1.7 gallons in the tank left over from what I'd put in which made the tank hold about 14.1 gallons.
I'd done this when I got the '99 coupe, but had lost the paper with all the data on it. Thought some readers might find it interesting.