For a while now I think big trusks should project (via laser scanner maybe) a large keep-out zone in front of them. My impression is part of the reason those trucks drive so much slower is their need to maintain a safe following distance, combined with cars that pass them cutting into that area. If we'd stop violating their safe-following zone they could drive faster and not slow overall traffic so much. This is not considering the speed limit often being lower for them.