Well, there's always the Cote d' Azur glitch.
After those tight corners, you get to a tunnel, curving to the right. So, don't brake for the corner, but wallride on the right at the last possible moment... you'll need to be doing ~160mph at least when you hit the little corner bit. Took me a while, but you'll be able to break out! A good way to test a car's top speed...