Long trip driving recommendation

K-Ken, how do you know that your mileage is different? I have yet to figure out my mileage when in hybrid mode since there is no way that I have found that I can track which parts of a drive are using the ICE and which parts aren't. In the 10 weeks that I have been driving my car, I have only filled the tank once. That was at 1680 miles and it took 5.4 gallons. I know I wasn't getting 311 miles per gallon in hybrid mode.

The only time I have ever driven beyond the EV range is my drive to work. It is 35 miles one way, but I only go to work 3 to 4 times per month. I tend to arrive at work with between 8 and 10 miles of EV range, so the return is about 25 miles in hybrid mode. My drive to/from work is 95% highway in relatively flat country (I live in central Indiana). I observe that the ICE comes on just after the EV range gets to zero, and then it cycles from low RPM to high RPM to shut down according to the needs of the car for motive power. Yes, there are times when only the battery is moving the car, even at highway speeds and no EV range indicated. Sometimes the engine and the battery show as motive force, sometimes the engine is the motive force while simultaneously charging the battery.

In other words, my Honda Clarity behaves just like any other hybrid powered car when the battery is discharged down to zero EV range. Sometimes ICE power, sometimes battery power, sometimes both.

One thing I know I WON'T do is an experiment to drive the car without charging it to test the ICE mileage. That would be the only way to truly determine what my mileage is in either city or highway driving. I bought this car to drive as much as possible on electric power. If I had wanted to drive it only as a hybrid, I would have bought the Accord hybrid when they came out. Which was my plan until I stumbled across the Clarity.

 

There is a long downhill on the route that I drive on a trip. I always start in EV mode to provide some room in the battery for regen. I then switch to HV. After going up and down the hill, I always have more EV range than before. If I was full EV, all of the breaking on the downhill side would not be going to the battery.


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I think we need more data points. Early on, I drove the car on the freeway when the battery became expended. The terrain was rolling hills but nothing steep. After subtracting the EV miles, it came out to be about 42 mpg (about 65-70 mph). Later, I did Two 200 mile loops to better determine the mileage, I started in EV in town before entering the highway then switched to HV. After subtracting the EV miles and refilling the gas tank (once after each trip) by double clicking the nozzle to make sure it was full. I averaged 52 mpg. On those loops, the weather was moderate in the 50's and 60's so I did not have heating or A/C on. The speeds here were lower at 50 - 65 mph and mostly in the 50s. The battery was at least half throughout. On a 1200 mile road trip, I averaged 48 mpg but with 4 passengers. HVAC wasn't on much and speeds at 60-70 mph. I kept the battery at about half most of the time. I had to do a re-charge after one fill-up and the mileage there dropped to 38 mpg for that tank (that was not included in the 48 mpg average). Re-charge seems to be very inefficient use of the ICE but it got the battery back up. During those trips, I watched the energy use pretty carefully. The car was terribly active in changing modes. Sometimes, the ICE engaged the front wheels directly. Others, the ICE was recharging the battery. At other times, it just went full EV, all while in HV mode. More interestingly for the discussion is that it could lose 5-6 miles of range (going uphill?) when needed and then it recovered it later when it was most efficient. I don't think the car has these options when the battery is expended. One other poster said he gets 42 mpg going 75-80 mph with A/C. That's remarkable mileage because high speeds and HVAC kills mileage for hybrids.

 

I believe the battery packs in most other pure Hybrids are less than 2kW.

 

There is one major difference compared to a true hybrid. A true hybrid uses a 150+ HP ICE engine with battery assist to haul <3500 pounds. When the Clarity is down to 2 bars on EV range (hybrid mode), it has to haul 4000 pounds on a <100HP ICE engine.

 

Mine uses both the ICE and the electric motor when necessary when down to 2 bars of battery power. Just like a true hybrid. 212 horsepower always available.

 

Yes, so does a true hybrid. I was trying to say a true hybrid uses a 150HP ICE engine plus battery (for a lighter car, since it has a much smaller battery), while the Clarity will use a 95HP ICE with battery for a heavier car. This makes the engine rev a lot more and cause the "angry bees" loud rev noise reported on this forum. When the battery is not fully depleted, the algorithm has more rope in using more EV energy to supplement the engine, and the result is much more smoother

 

The only reason I set HV mode at half is because the engine doesn't rev up as much to replenish the buffer as it does at 2 bars (normal EV empty). I prefer how it drives. Plus, I can reserve some EV range for wherever I am going.

The Clarity is similar to a hybrid as you say, it gets worse fuel economy due to added weight. Some PHEVs get worse fuel economy as they don't spend as much money on the engine knowing they will be run only rarely with the engine on (e.g., i3 REx has a low efficiency engine).

I haven't compared actual MPG numbers from switching at 2 bars vs switching at half in the Clarity.

 

Sport makes the cruise resume much quicker, although still slower than I would care for. I would engage sport when resuming cruise control on my trip a few weeks ago.

Edit: You can press the go pedal manually to resume as well, accelerate up to the speed you want and let go of the pedal and it will go to the resume speed (i.e., you can help it a little).

 

The Clarity has a total of 212 horsepower available at all times. Even when the battery is down to 2 bars. I disagree that there is any difference in the performance of the car between battery half full and battery at 2 bars.

As to the "angry bees", it seems to me that a technique that tries to avoid the high rev times is just wasting gas. I see no difference in "smoothness" either way.

I bought my Clarity for fuel efficiency which I define as using as little fuel as possible. Maybe my heartburn with the techniques espoused in the all above posts is that I view them as using more fuel than my technique. Use EV until depleted in all cases, then use gas until the earliest opportunity to charge the battery. If someone else's goal is to avoid a high revving engine, then so be it. But that can't be fuel efficient. Forcing the car into hybrid mode for highway driving when there is still EV juice available isn't efficient, according to my definition.

 

The difference between 2 bars and say 10 bars left on the gauge is buffer level. 10 bars gives more buffer, meaning long uphill stretches will be less likely to deplete the buffer. If the buffer gets depleted the power will drop to whatever the engine is capable of producing.

I wouldn't expect an efficiency difference between 2 bars or 10 bars as they are both hybrid mode, one just uses a larger buffer (I think it will deplete the buffer and not recharge it up steep hills, but I haven't verified that).

What you don't want to do for efficiency is charge the car back up (might be other reasons to do this). I would avoid HV Charge mode for any efficiency purposes, although in practice in my Volt I didn't notice a difference between driving in Charge Sustaining mode (like Clarity 2 bar remaining engine running as necessary mode) and Mountain mode to charge up some range and deplete that in Charge Depleting mode (same as using HV Charge mode to get to half and turn off and deplete charge).

Many of us like to leave more EV buffer in the battery to hold EV charge at final destination, so engage HV mode at half charge. This is not less efficient than running it down to 2 bars. However, you should try to consume all the EV range before your final destination to burn the least amount of gas possible.

 

PS The Clarity has up to 212 HP available at certain times (not all the time), depending on mode of operation. If the battery buffer gets depleted the car only has 100 HP available (whatever the engine can produce) or even whatever the generator is capable of producing (maybe 60 hp) if the clutch is not engaged.

 

My understanding (and experience with my Volt) is that I got more miles per KWh in town than on the road, so I try to have as much battery as possible if I’m going to be driving a lower speeds at the end of my trip. Because I don’t ever use the ICE in town, I have no idea what the gas mileage would be at low speeds. I’m getting around 45 on the interstate.

 

Make sure you check with the hotel about potential outside plugs. The Doubletree in Downtown Memphis plugged my Clarity in last night in their valet parking garage at no charge, the Hilton in Memphis let me plug in using a plug on the gate which blocks a valet area from regular parking. I found an outdoor plug near the swimming pool at a Hampton Inn there that I could use.... All for free. I’ve never seen a free public charging station.

 

How did you secure the charger to make it did not disappear overnight?

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It's not everywhere, but Volta charging is free. http://voltacharging.com

 

Following all of the EV or HV banter makes me want to just say "relax and enjoy the ride." Even on a 1000 mile trip, the difference between 40 and 45 mpg is only 2.8 gallons of gasoline - folks, we are living in the lap of luxury, in a super fun car to drive, that is as efficient as hell. This old fart grew up in a 1967 Mustang with a 289 V8, sucking wind at 12-15 mpg and $0.33/gallon (which, by the way, is $2.47 inflation adjusted); I can't begin to drive my Clarity hard and fast enough to severely dent the efficiency.

PS - the comparative stats are astounding to me (we are pretty lucky my friends):

1967 Mustang 289 V8 7.5 seconds; 200 HP; 282 lb/ft torque; 2758 lbs curb weight
(https://www.zeroto60times.com/body-style/classic/)

2018 Honda Clarity PHEV 8.9 seconds; 212 HP; 232 lb/ft torque; 4052 lbs curb weight
(https://www.tflcar.com/2017/12/2018-honda-clarity-first-drive-review/)

 

I’m using a small padlock to go through the hole in the release button so handle can’t be removed from car. Will not stop a determined thief, just the casual snatch and run, but it’s better than nothing. When at home, I close garage door close to cord so that charger brick will not fit under door.

 

Car and Driver measured a 0 - 60 time of 7.6 sec and Alex on Autos measured 7.5 sec for the Clarity PHEV. The TFLcar guy used an iPhone in his right hand as he drove with his left hand while he simultaneously watched the road and the speedometer to get that time. There was clearly a lag time of over a second using his very unscientific method.

 

I have not secured my charger the times I’ve plugged in public. I guess I rely on the goodness of mankind.