Pitted Early even yhough i had enough fuel.

My cars pitted with 3.9 litres of fuel in the tank when the most amount of fuel used in any lap was 3.7. This included the previous lap.
I hadn't changed the settings for at least 10 laps because I was away from the computer.

This is a definite bug.
I was racing in Turkey - F1 International Elite.

I'm pretty sure its happened to me before too.
.

It just seems to me, that drivers with certain attributes do mistakes like miscalculate their fuels and when to pit for example. I think it is not bug and you should just study those driver attributes. One of the deciding factor between players, who finds best drivers that way. I think it is meant to be that way, but can't say for sure.

Jason, This is definitely not a bug.

Your drivers pitted because they did not have enough fuel to complete the final lap.

Your stints were:

37 litres  - 10 laps,
41 litres - 11 laps
45 litres  - 12 laps
48 litres - also 12 laps

& then you tried to do 13 laps with just 45 litres

Your drivers recognised that they did not have enough to complete the last lap, ( they had 1 litre & 1.1 litres ) & so pitted for more fuel

I think you misread my message.
If you look at the logs The 48 litres should have done 13 laps - only just but there was enough fuel to do it as you will see on the logs. I pitted with 3.9 litres in the tank even though I was only using 3.7 and sometimes 3.6 litres per lap. This caused me to be one lap short on my last stint. 

Also my drivers are both level 19s with talent 20 and therefore should not have made those mistakes.

It can happen, but it's usually with low level drivers who have no defending (or low decisions) training.. but both your drivers are level 19 so that's weird.