I came across an interesting comment in an article I just found, and I am interested in other people's experiences... While it is obvious that coasting with the engine off uses the least fuel (none), this article mentions that keeping the car in gear and letting the wheels keep the engine turning uses less fuel (none?) than idling in neutral, which requires fuel to keep the engine running (look for "throttle-off fuel saving technology" in the article): http://carsguide.news.com.au/story/0,20384,21210480-5001701,00.html First of all, is this true of newer cars? And second, if this is true (ignoring engine-off coasting as an option in this discussion), would it be better to keep it in gear (thus going a bit slower due to engine braking), or to coast in neutral and use a little fuel, but gain more distance due to the increased speed? In my case, during my daily commute there is a long downhill stretch, which I usually take in neutral. This actually causes me to accelerate from ~60MPH to well over 70MPH, thus exceeding the 65MPH speed limit (even if only a little). However, during rush hour, I often have to use my brakes to avoid random lane-changers, or when traffic is moving slower. Could the use of engine braking to control the speed of my descent use less fuel than coasting in neutral and using more brakes? I can always drop to neutral toward the bottom of the hill to coast the rest of the way into town. Anyone have an opinion on this one?