Headlights - auto or not - are only part of the equation. If the weather gets bad enough, I turn on my hazard lights as well. The flashing lights really draw attention to a vehicle in a way that the constant glow of the other lights do not.
Whether it is because tail lights are red or because they no longer stand out owing to being in a steady state, I don't know. What I can say is that when I look ahead, trying to see though a wall of rain/snow/fog/... the only thing that cuts it for me are the flashers.
Also, keep it on low-beam setting and add your fog lights, if you have them.
The final piece of the equation is: slow the fack down.