Old cars they have a rear portion that cannot wind down. Below is the arch that is needed for clearance for the car's rear tyres. That is why the portion that is not above the arch can be completely wound down.
New cars they do away with that triangular section that is fixed. The whole glass can be wound down. But that arch below is in the way. So the rear part stops there, the front part can go as low as it can, into the door. The rear part just stops above the arch but inside the door the glass already went as far down as it can.
No leh, even the newer Subaru Legacies also cannot wind the window down the whole way due to the cut out at the bottom corner for the wheel arch. But then again it's also not really a problem unless you intend to stick ur head out the rear windows.