[MYST]

I thought the Megane [...] would be the one grabbing points.

Nonfractal, your Megane was faster on the straights than the winning Mercedes, however it lost ground on the  compound curve (top right of the track layout drawing). That curve is configured R4>R4>R3>R3>R2>R2. The Megane took the first part of the curve at Mercedes speed but then, as it entered the R2 section, it simply rolled gently onto its side. So I had to slow down. 
Your car is a few mm taller than the NSR and has a fractionally shorter guidebase which may explain the effect.