[IndyIan]

I live in an area that is basically a drumlin field, which means we have many many hills about 150 to 200 ft tall. The roads cut through them abit but it I think the longest perfectly flat stretch of road on my commute is about 2 miles. But most of the time you are going up and down.
So I pulse and glide with the hills which keeps me with traffic if there is any, and anyone behind me probably has no idea I'm coasting alot of the time. On a few hills I am speeding 25km/h over coasting in neutral. Also with my neon, 50% throttle will get me up the hills at 100km/h and then I coast down to 80km/h and then gas it up the next hill. For me the hills allow me to pulse and glide while maintaining speeds between 80 and 100km/h which is reasonable to do in light traffic.
I'd think slowing as you climb a hill is a bit counter productive as it keeps your engine in the inefficient low throttle opening zone for longer. The gravitational energy you have gained is equal at the top of the hill wether you idle up or use %50 throttle. In high drag vehicle I'd guess you want to always stay slow but for a streamline car probably you want to stay at 50 to 70% throttle all the way up and then coast down.
Ian