since the rears define stability at speed, mixing is stupid. Sure it would be illegal here, too. You will also get completely useless ESP because it's assuming the brake efforts at the rear wheels do something. It is not the fastest system ever and provocation to overcorrect is easy to achieve.
I drive snow and ice four-five months per year not the four-five weeks of the uk and have done for the last 14 years. I had the Octavia activate ESP at speed last winter twice in some truly atrocious conditions. Both times it was the back end that lost traction, in one case throwing me halfway across the other lane with zero warning. No funny camber, just too fast at 55km/h... and zero grip. Second one was melting snow on sheet ice at 60km/h.
This is why I offer the opportunity to drive the ice each year, to learn and push in a safe environment.
We just drove up here tonight in snow and considering it's *always* the back that goes first....nope nope nope.
- Bret