Fuel levels

Playing 26 my team career on PS.

Have noticed an issue between selecting the amount of fuel in pre-race screen and then it automatically bumping up a bit when you start the race.

Say you select 18 laps of fuel, when you start the race it will initially show 18 laps on steering wheel then bump up by a few tenths, say 18.2 just before the race start sequence.

Wondering if this could be related to fuel or other car developments. I do not have any fuel efficiency upgrades. 

Anyone else noticed this or have any thoughts as to why it happens?

🖖🏽