The biggest problem is how well are the other vehicle's headlights aimed. When i'm on the highway at night, i find that the Mercedes and Range Rovers with their HIDs are never an annoyance, because the lights shine at the ground rather than into my windows. GMC/Chevy SUVs and Pickups seem to be the worst offenders - they've got the xenon lights, but they're just a drop in replacement for the standard headlamps, so they shine straight out in front.