I find the impatient car drivers cutting in and out of the lines of traffic more dangerous than the loss of speed by the trucks on the hills. I've seen (a few cars behind the action) a few accidents caused by the left lane line getting filled by right lane passers who are unwilling to wait. The speed changes and land changes are more predictable than the right lane passers. If I only got a dime for every time a right lane passer pulled in the braking distance I have left in front of me while waiting in the line to pass slower moving vehicles in the right lane I could pay for a few tanks of gas.