Per Diem
Just to enlighten the discrepancy between actual and theoretical Per Diem:
it's paid per hour, so every time you start off on a trip later in the day, or return in the morning, you don't get 96 EUR, but only 20, 30, 40 or so. With around 30 trips/year, that's 60x less Per Diem, so roughly 4000 EUR less per year than the theoretical figure of 180x96 EUR.
Fly only long trips, you get a little more, but then again you'll spend more too.
Cheers,
TRNRD