I just completed a 2000 mile trip yesterday. I was amazed by the extremes of driver courtesy I witnessed. Some truckers would signal that I was clear, others (most) did not. I rarely missed signalling a truck he was past, except when one decided o pull in so close it was BRAKE TIME. When I was signaled in, I did flash a thank you. As for cars, Many seem to think you can stop on a dime with nine cents change, but a few were nice enough to signal I was clear. On a few occasions I had to stand on the brakes when someone decided MERGE means accelerate at a really slow rate in a travel lane instead of in the entry lane. Lots of lane available they just wanted in NOW. Can;t risk being behind the big bus thingie! All in all it keeps you awake!