FWIW-
I accelarate fast, briefly, then coast as long as possible with the clutch in or the shift in neutral. Idling the engine,or even turning it off on long coasts, has improved things for me. (got 72 the other day on a 1.5 mi errand.)
Although "ChrisY" appears to suggest that she's sacrificing safety and control at times (i.e., "... even turning it off on long coasts ...) her idea of "... accelerate fast, briefly, then coast as long as possible ..." works with CVT models as well.
Experience has shown me that there is a point where the MPG and speed are both so low that you really won't lose too much more if you accellerate anyway, which increases your speed, thereby causing you to spend less time in what I call the "low MPG - low speed zone." If you're not familure with with this, just be alert for it and when you see it happening, when you're down in that low MPG-low speed "zone", odds are you'll know it. It's a combination of watching not only the MPG gauge(s) but the engine RPM as well as MPH.
But keep in mind at all times when driving, common sense and safety first. As with the rest of us, time and experience will show you what I'm talking about.
Hope this helps some.
Fred