Tim- In the techniques you use, you didn't mention "driving with load" (DWL) as a technique. In my experience, its not enough to drive slow in areas with lots of terrain changes. You need to take advantage of momentum through the downhills (gaining speed as you decend) and minimize engine load on the uphills (feathering the gas pedal back as you ascend until you reach the crest of the hill). DWL has worked wonders for my last several tanks.