Last week I learned an approximate shutter speed to use. The week before that, I learned that tracking with the subject directly behind you sucks.
This week, I took the information I learned and applied it. a shutter speed around 1/40 to 1/60 sec and I made sure to keep my subject in the opposite lane.
Coming up this week: adding flash equipment into the scenario. A single bare flash as fill with the sun as a backlit-key light. Hopefully with a different vehicle, but I'll use the Saab again if I have to.
I also want to get a lower angle on the moving stuff, but to do that i'd have to put my camera on a pole and lower it down against the highway at 65mph. Not a fan. I'll probably do some panning instead.