Is it as efficient as the second generation?
Wayne Gerdes - CleanMPG
- Oct. 5, 2009
2010 Prius-III - $22,400 to start and 50 mpgUS combined.
Just like the second generation Prius-II, the all-new Prius-III takes some time to understand its idiosyncrasies. In the Prius-II’s case, its maximum city/suburban fuel economy came almost instantly as I was fortunate enough to experience with Dan Kroushl's 2004 Prius-II during the Prius Marathon attempt 4 + years ago. That event showed the world what the Prius-II was worth on an around town course when we ran it from topped off to empty covering 1,397 miles at 110 mpg. Its somewhat poor highway numbers is where the real frustrations came about however.
Back in late 2007, I was offered the opportunity to take a 2006 Prius-II out on a lengthy week long plus, city/highway daily grind drive. It took over 800 frustrating miles before the Prius-II’s higher end highway capabilities, namely SHM with IGN 14/TPS 18, finally revealed itself
Given the Prius-II’s city and highway Hypermiling tools we have at our disposal, would the 2010 Prius-III prove as fuel efficient even with its larger 1.8L atkinsonized Corolla engine? The EPA Fuel Economy figures lead us towards that reality but the nagging questions remained as we experienced in Napa Valley during the 2010 Toyota Prius-III
preview launch earlier this year. Namely, the lower highway FE achieved on the 102 mile segment and in particular, the 6 mpg over report of the OEM FCD vs. actual miles traveled and gallons consumed from top off to top off.
Afforded the opportunity to drive from Chicago to NY on a single tank of fuel in both the Prius-II
last year and the Prius-III
this, how do the two generations of Prius’ compare and which came out on top?
2010 Toyota Prius-III Chicago to NY highway review drive.
A light headwind when leaving Chicago. 70.9 mpg at 53 mph
per the OEM FCD was the result as I stopped in NY for the night.
First fill up
71.2 mpg at 50 mph average speed and 801.1 miles into NY on a single 12.330 gallon tank of fuel.
This calculated out to an actual 64.97 mpg from top off to near empty and a top off.
I gave Harry Clark a country road and highway hypermiling clinic over the final 250-miles.
And here again the 6 mpg OEM FCD over report vs. actual as experienced in NAPA reared its ugly head again. Working to maintain the 70 + mpg target and to end up so short is more than just a frustrating experience.
Even stronger headwinds coming home
72.8 mpg at 44 mph avg. home with a 10 + mph headwind. – 815.9 miles on 12.178 gallons = 67 mpgUS actual.
With the 6-mpg over report now a fact vs. theory, the new yet elusive all-highway OEM FCD target of 76 mpg minimum was just not in the cards with that 10 + mph headwind most of the way home. The overall average was somewhat disappointing at 65.978 mpg although an all-highway drive in a Prius from Chicago to NY and back on a single tank with headwinds in both directions is still an OK drive none the less.
Chicago to NY and back drive. 1617 miles at 72.0 mpg (per the FCD) and 47 mph average speed including hourly rest stops.
66.0 mpg actual with actual average road speed of ~ 53 mph.
There is a still more to learn about the Prius-III’s highway capability as the HSI is more a demand indicator than an actual output. These are Manuel Santos’ words and I wholeheartedly agree with that assessment.
There appears to be at least two and possibly three modes of Warp Stealth. One with no fuel consumed at ~ 980 RPM. Another where there is some fuel consumed from 1/3 up the EV side of the HSI to the EV threshold bar. The iFCD holds in the 150 – 220 mpg range while you are pulling off the pack more than just to maintain the engines RPM while the Prius protects MG2 from a minor over rev. Almost like a NICE-On in fact?
Near the EV threshold and IGN/TPS at 12/18, there is a high FE mode that I have no idea what to do with just yet. I saw it a number of times near transitions but it is not a power addition mode but more like a slightly higher speed glide mode without the drag of WS?
Transitory SHM – IGN 21/TPS 18/RPM 1088/FE 90.0 mpg
And of course a std. SHM using TPS of 18 – 19 and IGN at 21 - 22. SHM is a lot harder to hold in the Prius-III vs. the Prius-II as 1,088 RPM from the 1.8L is just not enough power to hold speed with any impediment be it wind, rain or slight ascent. You really have to pay attention with this to grab as much FE as possible from it as you will be transitioning into and out every few minutes.
SHM – IGN 22/TPS 19/RPM 1088/FE 78.5 mpg
Putting it (P&G, SHM and WS) together in std. heavy Chicago Rush Hour traffic.
For a standard Chicago style stop and crawl
, the 2010 Prius-III allowed 87.8 mpg per the OEM FCD which was more like an 81 mpg actual.
Chicago's Circle at the Dan Ryan – Kennedy - Ike Interchanges, to the Kennedy Junction and onto the Eden’s heading home during morning rush hour.
With over 1,600 miles of highway and 150 miles of city behind the Prius-III’s windscreen, let us place all that we have learned and put it to the test... Oh how I was waiting for this day to come
Northern Illinois to Northern Milwaukee, WI highway drive
Last weekend I again had the opportunity to again take a 2010 Prius-III out on the highway on a short trip to Milwaukee for an EBH_install
. With a 95% highway commute ahead, was the allusive 70 + mpg highway drive available or not?
Leaving my parents with their 2010 Prius-III showing 40.1 miles and the FCD sitting at 65.1 mpg since the last fill-up, it was time to try again.
Although temperatures were not optimal, 62 – 65 degrees F, and the Prius-III’s tires were sitting at just 34 psi all around, it was going to probably be my final chance of the season with day time temperatures falling almost daily in Northern IL/Southern WI. Winds were absolutely calm so as to not skew the mpg results one way or the other. I hit the Interstate after ~ 5-miles with a warm-up hit and the FCD now sitting at 65.2 mpg.
Accelerating to the std. 50 + mph and using the Prius-III’s brand of SHM at IGN 22/TPS 19 whenever available, I was going to try something a little different regarding Warp Stealth on the descents. The Prius-III unlike the -II uses fuel under a WS like mode (not just the –II’s transition spurt either) whenever you surpass about 1/3 up the EV side of EV threshold on the HSI as described above. What I did was to leave the power demand bar on the HSI set between charging and the bottom of that threshold during any WS event making sure no fuel was used. I would immediately and almost forcefully move to SHM in the trough and DWL while climbing any small hill or overpass ahead. Of course you will fall out of SHM during climbs and at that point, I would not allow the IGN to move no higher than 25 while staying at least 5 mph above the minimums. I arrived at the EBH install with the FCD showing 71.9 mpg and maybe 3-miles of suburban roads off the Interstate to the EBH install garage.
|Miles traveled||FCD (mpgUS)||Gallons consumed|
|40.1 miles||65.2 mpg||.615 gallons|
|89.1 miles||71.9 mpg||1.239 gallons|
Using the above, the 49.0 miles traveled consumed .624 gallons = 78.526 mpgUS (per the FCD). Having experienced the Prius-III’s FCD over reporting of 6 + mpg on my parents and the Review Prius on the trip to NY and back (an ~ 8% over report), the actual FE from IL to Northern Milwaukee during this drive turned out to be 72.24 mpgUS.
Finally, an actual above 70 mpg highway drive including the 8% negative OEM FCD offset. I now believe the Prius-III can achieve the Prius-II’s highway FE numbers unlike my experience earlier this summer on the Chicago to NY review when I was unable to achieve the same. In warmer day time temps, it is possible that the Prius-III could break the 48-Contiguous State WR at 68.5 mpg although it will take one very hardy and experienced team to maintain an ever constant vigil on the Prius-III’s tight SHM band. It is harder to maintain than in the Prius-II but it is there for the taking. Additionally, using a much shallower WS than what we can get away with in the Prius-II appears to be yet another key to the-III’s highway FE prowess. Too bad about the OEM FCD displaying 6 + mpg from actual on so many early Prius-III’s but simply work around it with a 6-mpg offset at any glance
Oak Creek, WI library to home for high FE...
With the highway experience completed in the early morning, I wanted to find out if the 2010 Prius-III was as capable as the Prius-II in a high FE slower speed drive. I pressed up the tires to 60 psi at the EBH install and set out. Coming home, the temperature had risen to 69 degrees so I stopped at the Oak Creek library where the MiHG has its meets. I have driven and ridden in a Prius-II from my home to this library in similar temperatures with little to no wind twice coming in at 99.3 mpg and 101.1 mpg. This course consists of 28 stop signs and 5 stop lights (3 of which I was stuck at being the only person on the non-priority roads
) over 40 miles of very rough frontage roads. Three miles of this drive was on brand new asphalt with one section almost hard gravel as I had to turn around due to this section of Interstate’s frontage road being torn up and closed.
Using Pulses that would begin at a min of 20 mph when I could glide to that that low and pulling back into a Glide before 35 mph, I was trying to maintain the 8% offset SG-II's iFCD at 2 to 5 mpg above the current speed. RPM was holding below 1,480 RPM in most cases with any higher R's hurting the aFCD through the next cycle. Climbing as high as 1,700 showed how much fuel the 1.8L would consume with little additional acceleration to shorten the burn and it was very painful to watch
We still need time to hone rates and ranges compared to what most of us have experienced with the Prius-II. All said, it all still works (Pulse_and Glide plus Warp_ Stealth in the Prius II for maximum FE …
, A few quick notes on the Prius-II from a non-Prius-II owner … Page 2
and New Prius - "Super Highway Mode" Technique (SHM)
) with the Prius-III... Just with a few tweaks
The OEM FCD immediately went to 99.9 mpg and it never dropped. The SG-II with its 8% negative offset inserted however showed a low of 91.8 mpg with much of the drive in the 93 to 96 mpg range. The final result ended at 97.1 mpg with the OEM FCD of course still pegged at 99.9 mpg. What this told me was the 2010 Prius-III’s slower speed capability cannot match the Prius-II’s capability by at least 2 mpg. This was not a side by side but driving both to their max on somewhat poor road conditions, with solid impediments (stoop signs) almost every mile but little traffic to contend with which tells me the 1.8L does not have the same capability as I also experienced at the Prius-III launch in Napa Valley during the many FE challenge courses we drove earlier this year.
Final Oak Creek Library to home. 97.1 mpg actual per the SG-II over 40.3 miles.
There is still more to learn from one of our favorite high fuel economy vehicles and as of last week, I have new found respect for the mighty Prius-III just as the -II before once driven under its own brand of SHM for the very first time.
As far as the question which Prius generation is the best in terms of pure fuel economy, how about I say both are excellent vehicles with the 2010 Prius-III being more the more comfortable of the two. On an all-highway drive over any lengthy distance and knowing what I know today, I would drive the 2010 Prius-III. For a local city or suburban commute, the 2004 – 2009 Prius-II will take on any vehicle on the planet other than a PHEV or BEV. The 2010 Prius-III will be on its heels in hot pursuit however.
I hope you discover what your 2010 Prius-III is actually worth vs. what the EPA tells you it is too