There has to be some reason. I'm not sure I ever owned a vehicle without it.My salesman told me that because of the coolant reservoir's proximity to the turbocharger and related plumbing, a special heat-resistant construction was required. I'm just repeating what I was told, and am not taking a position on the matter.
The black reservoir on the 2.0T does indeed stay very warm for a little while after engine shutdown. Too hot to touch, at least for a time.
There has to be some reason. I'm not sure I ever owned a vehicle without it.
Bingo…..The reason is that the 2.0 runs stupid hot. It's clear on the 3.6 variants