Oh wow, that seems a lot smoother than all my tests yeah. Having your file shall help me understand what's wrong whith my model, thank you.
is there a specific tool or method to be able to smooth the road from Google API like you did ?
After the initial download, I used the "Add / Remove Detail height from Google" tool on the roads and areas like peaks and valleys. You'll probably need to do some more.
I will send you a link directly to you your RD profile.