HV Only Gas Mileage

yes, and I think its delightful to drive a "full size" heavy car that rides smoothly on the highway and get mileage of a much smaller lighter vehicle. Of course, I'd love it if battery technology gets us lighter weight too-- but in the interim, the weight seems to make the car feel really solid on the highway.

My work has a Honda Fit, which honestly is a great car, especially for around town. But man, get that thing on the freeway and the road noise combined with light weight make it sensitive to any wind and vibrations-- or at least way more so than Clarity.
 
David Towle said:
I think you are saying the engine was on even though on the display there were no arrows going from the engine to the battery or wheels? And you determined this from hearing the engine?

On the highway I always have the stereo blasting so if that happened I easily could have missed it. I will turn it down and check more closely my next ski trip.
Click to expand...

Yes to the first part. I determined that the engine was staying on by the fact that the "power indicator" ring in the instrument cluster never turned blue, not even the part to the first major tick mark. Also the instantaneous mpg gauge didn't go all the way to 80, though it did go fairly high indicating that the engine was in a fairly low power state, even though it was kept on.
 
David Towle said:
Great information and pretty compatible with what I found, thanks.
I have found I get about 35 miles of winter range on the batteries alone at highway speeds, so shouldn't you be deducting that from your mileage total? Therefore (805-35)/20.159 = 38.2
Click to expand...

David Towle

Ran HV mode exclusively for 356 miles. Ran 4 days just as I would normally do...nothing out of the ordinary. Wind less than 15 mph entire testing period. No precip. As a matter of course, I run 89 octane pure gas (non-ethanol) in the Clarity. GVW = 4260 lbs. I conducted the test using normal HV mode. I never used ECON or sport mode.
  • Temps 33 to 44 f. 1 day in the 40's. 3 days 33 to 38 degrees f
  • 80% 2-lane and 4-lane roads with posted speeds limit 25 to 55 mph
  • 20% Interstate posted speed limit 55 to 70 mph
  • 52 EV mile range to start...11 mile range at finish. Never charged the Clarity during the 7 day period.
  • I estimate 12 mile range gained through native regen...(ie) never used paddle shifters
  • filled up with 6.80 gallons after 303* miles = 44.55 mpg in HV *after 53 miles deduction for EV*
I also placed a OBDll device at the beginning of the HV test. The OBDll device has a SD card installed and I programmed it to start a new log file every time I start the Clarity. 31 log files generated 81,800 data points. Ancillary info below

Speed breakdown
  • 1 - 35 mph 39.4%
  • 36 - 60 mph 42.3%
  • 61 - 79 mph 18.3%
RPM breakdown
  • ‹ 1000 - 40.47%
  • 1001 to 2600 - 56.59%
  • 2601 to 3600 - 2.39%
  • 3601 to 4445 - 0.55%***
***This RPM occurred under the following conditions. EV range 12 miles. Travelling 55 mph up a 6% grade for 5 miles. These RPMs were recorded 3/4 of the way up and only for 42 seconds. I could hear the engine whine for sure but did not consider it egregious at all. Sounds to me like any other 4 cylinder when being asked to handle a arduous task.

Engine clutch mechanism engages as I expect on all roads where speed limit is ~45 or greater. When maintaining 45 mph speed or greater...it goes off when climbing noticeable grade and when descending a similar grade. Stays on majority of the time when maintaining speed. Very pleased with performance of the engine clutch.

Bottom line is 51.3 mpg in HV mode gathered in late summer as reported earlier. 44.55 mpg under mild winter conditions.

Hope this helps.

Good luck.
 
Last edited:
Clarity_Newbie said:
  • 52 EV mile range to start...11 mile range at finish. Never charged the Clarity during the 7 day period.
  • I estimate 12 mile range gained through native regen...(ie) never used paddle shifters
  • filled up with 6.80 gallons after 303* miles = 44.55 mpg in HV *after 53 miles deduction for EV*
Click to expand...
Nice data thanks. Your driving conditions are a lot slower than all the ones I've calculated mpg for.
BTW your mpg is about 2 higher than you calculated, there is no reason to subtract off the 12 miles from regen. Just subtract off the 41 EV range used.
 
David Towle said:
So I guess no one thinks the 33-38 mpg runs I recorded is out of the normal range?
Click to expand...

In reading through this thread, one thing that stands out to me is that your data seems to be nearly all at 70+ MPH. Losses go up very dramatically with speed. Have you done some testing in the 55 to 60 MPH range? I would think that you would consistently be 40+ MPG at the lower speeds.
 
David Towle said:
But there's always significant losses in the process. If there wasn't, the mpg penalty for driving in hills would be close to negligible.

So I guess no one thinks the 33-38 mpg runs I recorded is out of the normal range?
Click to expand...
I drove in 38 F weather for 384 miles .. got like 38 mpg on ICE engine exclusively in HV mode (speed was in 70-75 range).
 
With some more winter driving under my belt, I notice MPG can be MUCH worse with heater turned on. I suspect that the engine exits Atkinson cycle to generate heat, is there a way to check this with OBD2 scanner? Driving to Chicago cold weather and I was getting 30 mpg, I turned off the heater and it jumped to 38 mpg. This was calculated using trip computer. Driving conditions were the same. I suspect Econ (instead of Sport) mode might help here, will try next year.
 
Viking79 said:
With some more winter driving under my belt, I notice MPG can be MUCH worse with heater turned on. I suspect that the engine exits Atkinson cycle to generate heat, is there a way to check this with OBD2 scanner? Driving to Chicago cold weather and I was getting 30 mpg, I turned off the heater and it jumped to 38 mpg. This was calculated using trip computer. Driving conditions were the same. I suspect Econ (instead of Sport) mode might help here, will try next year.
Click to expand...
I don't think the engine can do that. Even in Atkinson the efficiency is only 40%, the remaining 60% goes mostly into the cooling water (with some out the exhaust and some to heat loss to the air)
 
Viking79 said:
Honda uses i-VTEC to simulate Atkinson cycle, it isn't true Atkinson engine. It can run either Otto or Atkinson depending on which cam profile it uses.
https://www.hondainfocenter.com/en/...ng/Atkinson-Cycle-2-0-Liter-4-Cylinder-Engine

It is just a thought that it needs the extra power as heat (either electric or waste) so it runs the Otto cam profile. (Hypothesis)
Click to expand...
A feature I didn't know about, thanks! I don't think it will affect heat rejected to the cooling system much though.
 
Getting around 50-52 MPG freeway driving in mild weather with the cruise set to 65MPH and HV engaged. Significantly better than my VW GTI in a much larger vehicle.
 
I have two data points to add.

First was a round trip to Colorado Springs and back. Temperatures were in the low 30's in the morning and mid-40's on the way home. I hate the heat set on 65 the entire time. CS is at a higher altitude than we are so I was climbing steadily on the way there (in the morning) and coming back down on the way home. I started with a fully charged battery and a full tank of gas. I drove 168 miles, used 3.685 gallons of fuel and 8.23 kWh of electricity. That works out to 45.6 mpg with a total cost of $7.43. I look more at my cost per mile since that encompasses both gas and electric operation and that worked out to be $0.04423/mile.

Second trip was to Cheyenne and back. This involves a drop of about 1000 feet, then climbing about 2000 feet on the way there. Weather was about the same but there was a vicious (30-45 mph) headwind on the way up. I drove 208.6 miles, used 4.836 gallons of gas and 8.27 kWh of electricity. That gives 43.1 mpg and a operating cost of $0.0586/mile.
 
MNSteve said:
Question for you mountain dwellers: Do you see your EV range actually increase after a long period of downhill driving? I've never seen any tangible indication that regen is capturing anything other than the power indicator dipping into the "charge" range.
Click to expand...

Read your question before I went out today. Had to go down a steep hill with a 50 mph speed limit. I did not use the paddles, but had my foot off the accelerator and was able to maintain speed while the battery gauge was in the green regen area. I had the estimated mileage on the DII and it slowly increased the estimated mileage one tenth of a mile at a time until the hill leveled out and i needed accelerator to maintain speed.
 
Last edited:
MPower said:
while the battery gauge was in the green regent area
Click to expand...
Green Regent - the latest Marvel super-hero? Auto-correction can be so entertaining!

I know the Clarity PHEV limits HV CHARGE Mode charging to 57.7% of a full charge--does regular regen charging also cut off at 57.7%?
 
I edited and took all the fun out of your super hero.

I can answer your question. Regen does not cut off at 57.7%. I had nearly a full SoC when I turned down the hill. I started with estimate of 33 miles and was down to about 27.1 when it started adding 10ths. I think when I started down the hill I had used up just the top thick bar on the battery gauge.
 
Clarity_Newbie said:
David Towle
I also placed a OBDll device at the beginning of the HV test. The OBDll device has a SD card installed and I programmed it to start a new log file every time I start the Clarity. 31 log files generated 81,800 data points. Ancillary info below
Click to expand...
I'd be interested in knowing which device you are using. Tried a bluetooth one, but it's a pain to start the software on my phone every time...
 
I got about 52 MPG (readings from dash trip meter) in HV mode on a 180 mile round trip. Avg temp 60 degrees and sunny. 50% mostly flat freeway and 50% mountainous highway. And I've used the regen paddles quite a bit on the mountain curves.

Count me impressed by the MPG, I wonder what it would be had I not used the regen pedals.
 
Last edited:
In my experience this car does get considerably better mpg in mountains than on flat land. Because despite the climbing there are the many opportunities to regen in mountains that flatlanders never get. I’ve seen nearly 55mpg manually calculated over a full tank of fuel tearing thru the Rockies. And some of the long 20+ mile descents out of mountain passes have added as many as 4 bars to the battery gauge with engine off the entire time. But I’ve never done more than low 40s on an interstate run without the mountains. Often mid 30s if cruise control is set at 78 or so.
 
Just got back from a road trip to Chicago. Temps in the high 20s-low 30s with heater running (cabin temps at 70F) and speed consistently between 70-75 netted me an actual HV mileage of 33.4-34.5 mpg. I know for a fact it is much better in the summer.
 
You must log in or register to reply here.
Back
Top