Had to drive 200 kms, lots of highway and some city. That's almost half my tank so I decided to P&G, filled up at the end, and got 54 MPG which is pretty much normal for me (drafting or driving slow).
On the highways I was running late, so I was pulsing to 70mph and gliding to around 55mph. It wasn't going well. My pulses were almost longer than my glides. I decelerated pretty fast as soon as I clutched in. I think there is too much air resistance at that speed, and my tires probably ought to be overinflated.
Later on I was pulsing to around 35-50 mph and gliding down depending on the speed of traffic and limits, and it was much much smoother. I could easily glide twice as long as my pulses. I suspect I made up for a lot of the MPG at this stage, since my gauge was going down faster than normal to begin with.
Advice?
Also, today on the highway I pissed off an ambulance who was driving behind me (only 1 lane). I would speed up to 110, and he speeds up to the same, then I glide down and he's right on my tail, then suddenly I would pull ahead and repeat. Then I saw him flashing his brights in my mirror. Finally he got an opportunity to pass me, so he went ahead and started driving 50mph in front of me, glaring at me from the side mirror. So I just P&G at a lower speed until he lost interest and drove away.