Probably said before, but in the garage screen, in the main setup tab page, when you press + for adding or - for substracting fuel, there are certain track/car combos where the fuel quantity remain the same after pressing the key, and the achievable laps can remain the same or increment or decrement. I guess, internally the app computes decimal quantities. But it's not intuitive, I guess if you press + it just should add one liter or gallon, natural integer numbers, plain simple. Well, or show the decimal part also.
I've started ignoring that altogether, even if it's right, and use the following method: Put a full tank of fuel in the car Do three to five timed laps in practice Note fuel usage with the S397 HUD per lap, take the highest value to avoid underfuelling Multiply number by amount of laps to determine how many litres in total. Example: 2.9l per lap x 20 laps = 58 litres. Add one extra litre for the first lap as with some cars you can use way more at the start. Race. If doing pit stops, then you'll have to plan in advance.
