Found the Sweet Spot!!

Yup. This car doesn't go on short trips. I'm talking about trips of 100+ miles where fully-warmed up is the default. And before I hit the freeway, the engine comes to a complete stop, so the idle check is done for sure. So I'm driving along at 60 mph getting about 50 mpg. If I then speed up to the "magic" 73 mpg, I'm showing 44 mpg. It is no sweet spot for me, that's for certain!

Some days the mileage is just amazing for no logical reason. Other days not so much.

 

I did some reading Wayne had posted about his "Super Highway Mode (SHM) Technique" awhile back and he uses the IGN function on his Scanguage II to find the sweet spot (if you have a SGII).

Basically, with at least 6 bars showing on the battery he pulses to 18 IGN (approx. 56 mph) and glides down to 14 IGN (approx. 50 mph) but then maintains speed as long as possible at 14 IGN. He reported that IGN of 14 when held at that number reports 70+ mpg for as long as you can hold it there.

Here's a quote from a thread of his...

Quote..."While driving to IGN14, when you reach 6 bars, there will be an initial area where 70 + is not available. 60 + is but not 70. This has to be a lower 6-bar SoC state but I am guessing on this? After a minute or two more of highway charging, the high 6-bar state arrives and that 70 + SHM is available afterwards." End Quote...

Obviously, it would be tough to be on the highway to consistently go 50-56 mph without getting run over but on late night or uncongested traffic it's a good technique to try out. I have a 700 mile round trip coming up next weekend and on my drive to my destination I'll be traveling from 11pm-6am so there should be plenty of room on the highway to test this out.

 

119 or 120 puts me in "get a ticket" territory. I might try a little slower, not faster. No point saving a gram or 2 of gas only to have to pay a fine.
Speed limit here is 110km/h, you should get away with 8km/h over the limit but you won't get away with 10.

 

Here's info from the same thread I previously quoted...think it was from "Dan"

Quote "Started a new Super Highway Mode Revisited thread where I think I have the mystery solved...A few years ago Wayne tipped me off to some really nice behavior on the Prius at low RPM. We've been able to replicated fairly regularly with the following recipe and SG gauges (TPS, IGN, SOC, RPM):

Do highspeed P&G with Warp Stealth until SOC is 61% or higher.
Ensure that block temp is over 165 degF (70 c).
Switch to CONSUMPTION on the MFD (castle display) to watch the instant MPG bar.
Get up to a speed of about 62-65 mph.
Now slowly ease off the gas pedal until you can hold a reading of 14 on IGN and 18 on TPS.
You should see your MPG bar at something between 75-85 MPG.
Hold this pedal position for 7 seconds and you should see TPS drop from 18 to 17.
Once TPS drops you should see the MPG bar jump to 85-95 mpg range.
Hold this "SHM" glide for a long as you can, then go back to step 4." End Quote