Engine durability

[ChriZ900 0]

I was testing different career's about AMG Mercedes and F1 Sauber. Both of them start with the same expected lap durability for the engine parts (25%-150Laps;50%-209Laps and 100%-377Laps). Is this right? I didnt test a race just watched at the laptop at the beginning of the career without drive any lap.
I was wondering about the scale with patch 1.05 changed for 25% race distance. 
If you set 61 average laps for the first 6 races. So in a 25% career you have 96 laps race time and the rest for practice (54 laps/6=9laps per race weekend for practice)
In 50% 186 laps (23Laps/6=3,8laps per race weekend for practice) in 100% 366laps (11laps/6=1,8 laps per raceweekend)
I know I dont know the right algorithm Codemaster used and the correct wear per lap but just with a fresh career the expected laps which Codemaster tells us shows this.

It is crazy that the best and the worst team have the same expected lap durabiltity for the engine parts.

[Scottishdude007 0]

dont know how this is happening but in my career mode doing 25% races after 5 races and practise sessions my gearbox is only at around 15% worn .Everything else wears away quickly just not my gearbox and i dont know if this is a glitch or if its because i do manual gears and am pretty good at it .is anyone else having this issue or know what is happening.id like to hear if anyone knows why this is .cheers.