A few quick notes on the Prius-II from a non-Prius-II owner …

[diamondlarry]

Originally Posted by Dan

And the new Super Highway Mode (SHM) technique was born . Wayne and I are certainly believers. There may be some refinement, but this may be the elusive 70 MPG highway technique that Prius pilots have been looking for.

Try it out and let us know if you can confirm a high MPG highway segment with it.

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I posted this in the Daily Grind when I should have put it here: I was able to get 71.* on the way to Hf and 72.* on the way home so I know that there is something to SHM . I can only imagine how much better my mileage would have been if I had known about the technique and how to manage it. This technique seems as though it's starting to blur the line between the Prius on the highway vs the HCHII on the highway.

[JimboK]

Wow, I wish I had seen the last few posts here before making the return trip yesterday. Makes me want to hit the highway again for a few miles just to check it out.

Originally Posted by xcel

There appears to be two modes to 6 bars of SoC for the highway driver .... When you see the quick flashing yellow arrows from the pack and MGSet mimic, back off just a touch and reapply when it disappears. I mean just a touch so that you are not using the pack.

I wasn't watching the mimic. Remember, the CV uses the MFD, so it's either/or. So on yesterday's trip I had the following set on CV's graphic screen: RPM (as always), battery kW, ICE kW, and iMPG, plus the always-present SoC.

62% seems pretty much to be the optimal SoC, which I'm guessing is the "high 6 bars" mode you're referring to; from earlier observations, 65% is when the 7th bar kicks in. Assuming reasonably steady RPM, from points above 62 it progressively discharges, and from points below progressively charges, until it settles in at 62. The further from that point the faster it moves of course, but that last percent or two may take several miles. Once at 62, then CV shows battery kW constantly fluctuating from negative to positive -- a CV equivalent of the quickly flashing yellow arrows.

But I didn't exploit it as you've described, not having seen this exact description of the technique. Instead, my goal basically was DWL at as low an RPM as possible and still maintain speed, and avoiding WS. I was running at considerably lower RPM than any previous long highway run, but still maintaining speed on the flat. Sometimes it was as low as 1200, more often in the 1300-1400 range. ICE kW could get as low as 7.

As I said, this was a hilly route, coming out of the foothills of VA, (I didn't consider a previous segment of yesterday's driving because it was largely a climb into and then a descent out of the mountains), though it gradually levels out somewhat toward the end. It's mostly 4 lanes, non-interstate, not too heavily traveled, posted limits mostly 55-65 MPH, with an occasional drop to 45 through small communities. Except for one short 2-lane segment (nothing but hills, lots of traffic -- an MPG-buster!), I felt safe letting it drop to 45 MPH on the uphills. But that often required RPM well above 2000 to maintain, and at one point, 3000. I deliberately avoided WS on the downhills completely except, as you suggest, as I approached transition to a sub-40 MPH glide. Instead I used regenerative coasting as needed to keep speed safe and (mostly ) legal.

Weather was pleasant, and m'lady was cooperative, so I ran without AC and with my window fully open and the right rear half open, enough for a good cabin breeze that she could still tolerate.

Total MPG for the trip was 60, the best I've done on the highway since getting the Hydroedges. It's important to note a net 700' elevation drop during the trip. Between that and avoiding climate control (which I've always used on previous highway trips), it's impossible to attribute any portion of the MPG improvement to driving technique. But I'm confident my technique didn't worsen MPG. Again, I'm anxious to get her back on the highway -- a flatter segment this time -- and try your technique.

CV also reports ignition timing, so I'll look for Dan's IGN sweet spot too.

Bottom line: It seems as though a lot of what we've come to believe about highway technique -- keep RPM above 1500 and liberal use of WS -- may have been turned upside down. I'm interested in hearing Hobbit's take on all this.

[Dan]

Originally Posted by hobbit

Can you watch RPM at the same time you're doing this, and
see if there's a correspondence? This is just ignition
timing you're talking about, correct?
.
_H*

Yes, it's just ignition timing. RPMs seem to be 1200-1300, but I'll have to watch it. Wierd thing is that IGN drifts to 17 while in that range, and if you hit that number you fall off mode in a very big way. So 13, 14 are good, and after that you don't get good again till you get up to IGN of 18 (I think). More on my return trip

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[Right Lane Cruiser]

Wow! Stellar work, guys! Wayne comes through again with something brand new and finally brings the Prius highway numbers up to par with the rest of its abilities. I love it!

[xcel]

Hi All:

___Her last short tank before Cheryl picked her up a few minutes ago. 355.6 miles on 4.375 gallons = 81.28 mpg. This was ~ 75% highway. Using IGN14 is a lot easier then fighting the iFCD and watching the Assist bars flash in and out quickly. Camp IGN14 in a low to MS highway once a high level 6 bar SoC is reached and she will allow 70 + in good conditions with a well setup Prius-II. The Prius-I must have had it also because I fought that thing tooth and nail for it out on the highway and she was showing me similar brilliance although I had no idea it was a timing display away

___Al, you can view IGN advance and RPM’s on the SG-II at the same time which is exactly what I did for her final RT. Cheryl is driving it home now and I setup the IGN advance to the upper left as priority with RPM to the right of it. You have to see it for yourself. The ICE is darn near idling between 1180 and 1280 when riding this “mode”. There is not a lot of power to be had of course (unless you want to give up the FE for a quick accel or a climb while not DWL to maintain traffic flow) but camp it and she shows you some darn nice highway numbers. I just do not think they are available up in the low 60 + mph range is all? Not really sure as I just don’t drive there that often?

___Jim, you have got to watch advance as it is very much like WS or Glide. There is a dead band within all 3 and you can hold it for a very long time. What I am interested is how the % SoC and current flows when you ride this somewhat elusive but newly tamed little beast

___Dan, I am seeing some 13’s and of course camping at 14 for the above 70 + numbers on average. On the downhill sections, IGN15 appears and SG-II is showing 100 – 140 with the MFD pegged at 99.9.

___The next question might be can the Prius-II take out an HCH-II on the highway? With the ease which IGN14 can be held, a SG-II equipped Prius driver that knows how to push tanks can beat a good HCH-II driver but place drivers of similar mindset and quality behind the wheel of each and I believe the HCH-II still has the advantage. In the stop and crawls or under 40 stuff, the Prius will eat an HCH-II alive but above 50 and the HCH-II is probably still more efficient? It is just a little bit closer now then it was in the recent past is all.

___Good Luck

___Wayne

[JimboK]

OK, got ignition timing plugged into the CV display. First observation is that it reports an ICE-off value of 19 rather than five. No significant driving observations yet, but hopefully it tracks linearly from there with how SG reports it, i.e., sweet spot = 28. If not, I should be able to duplicate Dan's discovery process easily enough and find the CV equivalent.

[Dan]

Originally Posted by JimboK

OK, got ignition timing plugged into the CV display. First observation is that it reports an ICE-off value of 19 rather than five. No significant driving observations yet, but hopefully it tracks linearly from there with how SG reports it, i.e., sweet spot = 28. If not, I should be able to duplicate Dan's discovery process easily enough and find the CV equivalent.

Interesting... This may be a SGII quirk, but it's definitely there. I may need to ask Ron what query IGN is tied to. Might not be "Ignition Timing" in CV. But whatever it is, if you have SGII, watch IGN.

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[tekn0wledg]

I looked into the RPMs on my Sgii when in the Shm state and here is what I saw. Keep in mind, this is rough as it's only been two trips on the highway for about 6mi each way [with the sun in my eyes]

IGN - RPM
18 - 1600+
17 - 1500+
16 - 1400+
15 - 1300+
14 - 1200+
13 - 1100+

It seems to indicate RPM = ((IGN - 2) * 1000)

These numbers seem fairly consistent when maintaining normal driving conditions. Hills will change the RPM a bit, but for the most part this was fairly accurate on my trip. Not sure what others have found though.

Also, I will say that the IGN of 14 and 15 seem to give about MPH * 1.25-1.5 as was suggested originally. I have to say I haven't see 75-90mpg on the highway too often, but I rode in that state for about 3mi today while within 5mph of the speed limit.

I also used the IGN as a guide for acceleration now, instead of RPM. This seems to provide the most accurate means of finding the ideal acceleration point for P&G sessions. I try to keep it inbetween 16 and 18, but to get up to speed quicker 18 is the best bet.

I will do some more research in the next few days. I'm slated to meet with JimboK tonight, so I'll be on the highway a bit longer than a I normally am, and thus can pay more attention to the numbers.