[piers.singer]

I don't think that you're driving too slowly, rather that you are ACCELERATING too slowly. Your engine will be more efficient at higher loads. When you accelerate at a higher load you reach your target speed more quickly, keeping your engine in a more efficient mode for a short time before allowing you to coast or cruise. By accelerating at lower loads you reach your target speed less quickly, keeping your engine in a less efficient mode for longer. This, as you have noted, will give you less time to coast so don't be afraid to step on the load pedal a bit, it's good for you.

As an aside, I raise an eyebrow at your hill technique. If you can coast up a hill whilst retaining appropriate speed then good on you but you shouldn't be accelerating downhill, this is expending petrol when you could just be letting gravity do the work. Once again, don't be timid about giving it some boot on the way uphill, your FE numbers will thank you.