Photo of Clarity Plug-In Hybrid in the dark
Clarity by Night

2018 Honda Clarity Plug-In Hybrid

Facts, Speculations, and Opinions

Updated November 16, 2017

11/16/17—Honda Press Release: A Flood of Information!

The very detailed press release Honda issued today for the Clarity Plug-In Hybrid delivered the information prospective buyers need to make an informed purchasing decision. The highlights:

The good news is that the $7,500 federal electric vehicle tax credit can bring the price of the Touring model below $30,000. The bad news is that the 2018 tax reform being proposed by U.S. House of Representatives eliminates this tax credit. The bill was sponsored by Republican House member Mike Bishop of Michigan (not only the state where the Chevy Volt is manufactured, but the actual congressional district where the Chevy Bolt is manufactured).

11/16/17—KBB.comís "Electric/Hybrid Car Best Buy of 2018"

Kelly Blue Book®, has named the Clarity Plug-In Hybrid the "Electric/Hybrid Car Best Buy of 2018." The article includes a video review (from which I extracted the image of a silver Clarity Plug-In Hybrid appearing below).


The Clarity Plug-In Hybrid is the first widely available Honda since the Insight that represents a significant step forward in automobile technology (thereís an opinion right off the bat). The intention of this web page is to pull together some background information with the known facts about the Honda Clarity Plug-In Hybrid. Iím also offering my speculations and opinions.

Hondaís 11/17/17 press release answered the most important questions I was asking, but you will find many remaining questions (framed in square brackets) sprinkled throughout the text below.

—John E Johnson, aka Insightman    
(contact: john at this website)      

Photo of 2018 Honda Clarity Plug-In Hybrid
2018 Honda Clarity Plug-In Hybrid
(Click on image to go to Hondaís Clarity Plug-In Hybrid Site)

button to skip history section

Fuel-Cells First

Honda, the worldís largest manufacturer of internal combustion engines (ICE), looked to the future. The company realized the non-renewable resources required to power internal combustion engines and the climate-change effects caused by those engines would eventually make them obsolete. Honda, like many other companies, saw clearly that the future of mobility was electric. The company has announced its intention for electrified vehicles to comprise two-thirds of its global automobile sales by 2030.

There have been electric cars since the early days of the 20th century. The two main disadvantages that all electric cars suffer when compared to ICE-powered cars are limited range and lengthy recharge time. It used to be said that the range of an electric car is about the same as the range of an ICE-powered car with a red warning light glowing on its gas gauge.

Tesla attempted to address these problems by packing their cars with very large battery packs and then building special high-voltage/high-amperage "Supercharger" recharging stations. Still, the maximum range of the $94,000 Tesla Model S is a scant 335 miles and it takes more than 9 hours on a Level 2 (240-volt) home charger to achieve that range. Visiting a Tesla Supercharger recharging station can reduce this time to less than 2 hours, provided there are no other Teslas already occupying the chargers at that station.

Photo of 2004 Honda FCX Hydrogen Fuel-Cell Experimental Vehicle
2004 Honda FCX Hydrogen Fuel-Cell Experimental Vehicle

Honda decided to employ hydrogen fuel-cell technology to solve both the range and recharging problems of battery electric vehicles. The first viable hydrogen fuel-cell vehicle in the U.S., the 2004 Honda FCX V4 (the 4th version of the 1999 original), was produced in extremely small numbers and leased to a few government agencies in California. According to Wikipedia, it was the first fuel-cell vehicle to receive U.S. government certification for commercial use.

Hondaís 2017 Clarity Fuel-Cell car offers range: it can travel 366 miles between hydrogen fill-ups. And, unlike the lengthy recharge time for a battery electric vehicle, refueling the Clarity Fuel-Cell car with hydrogen takes only a few minutes. Of course, a big asterisk cannot be overlooked: there are only a handful of hydrogen filling stations in the world.

Photo of 2008 Honda FCX Clarity
2008 FCX Clarity Fuel-Cell Car

In 2008, Honda began leasing the first hydrogen fuel-cell vehicle available to real people, the FCX Clarity. It was rumored to cost more than $1M to manufacture, so it was not produced in significant numbers. But a very small number of people near Hondaís US headquarters in Torrance, California, were finally driving fuel-cell vehicles. Hydrogen filling stations were almost nonexistent, so Honda helped sponsor a few of them in the southern California area. The data Honda gained from the customers who leased this car helped them design the next-generation Clarity Fuel-Cell car.

Gas, Gasoline, and Electricity

Photo of 2013 Honda FCEV Concept Car
2013 Honda FCEV Concept Car

At the 2013 Los Angeles Auto Show, Honda unveiled this wonderful fuel-cell-powered Honda FCEV concept car. If you look closely, you can see a couple of styling cues that actually made it from this concept to the production Clarity. I personally hoped for ALL the styling cues to carry through to the production model, but this almost never happens. I was spoiled when the 1999 Honda Hybrid VV concept car became my 2000 Insight with virtually no changes.

Also in 2013, Honda brought to a limited market the Fit EV, a battery-electric vehicle (BEV) that offered a range of 89 miles. Available only on lease for $389/month (then $259/month in 2014), it was tagged by the press with the "compliance car" moniker, which implied Honda was making this car only to comply with the California Air Resources Board (CARB) requirements for manufacturers to sell a certain number of zero-emission cars or be prohibited from any selling any cars in California. The additional weight of the batteries made the Fit EV less fun to drive and its limited 89-mile range was eclipsed by competing BEVs. Honda discontinued the manufacture of the Fit EV, but still leases them as pre-owned vehicles.

For the 2014 model year, Honda released a plug-in version of the Accord Hybrid that could achieve an all-electric range of 13 miles. To test its viability, Honda made the Accord Plug-In Hybrid available in only a few markets in the United States. Unfortunately, potential customers did not believe the value provided by 13 miles of gas-free driving justified the carís $10,000 premium over the $30,000 cost of an Accord Hybrid. Honda discontinued its first plug-in hybrid trial after just a year.

Hondaís next venture into electric mobility was the lease-only 2017 Honda Clarity Fuel-Cell car. Although it is almost exactly the size of the Accord, it does not share the Accordís platform. The requirement to incorporate a large hydrogen tank behind the rear seats and a smaller hydrogen tank under the rear seats required Honda to develop an entirely new platform for the Clarity Fuel-Cell car. At present, the Clarity Fuel-Cell car is available only in California.

Honda then adapted the Clarity platform as the basis for the lease-only Clarity Electric car. Other than some external trim differences, the Clarity Electric looks just like the Clarity Fuel-Cell car. Inside, there are some necessary differences in instrumentation and one important additional driver control.

A special control paddle behind the steering wheel of the Clarity Electric allows the driver to select higher levels of electric power regeneration achieved under braking. The Clarity Electricís 25.5 kilowatt-hour (kWh) battery provides a nominal 93 miles of range per charge, and this regen paddle gives drivers the ability to stretch that range.

Some automotive pundits have decried the Clarity Electricís "paltry" 93-mile range, calling it a limited-range compliance car. However, there are no other comparably appointed electric vehicles at the Clarity Electricís price point. A Chevy Bolt can go 238 miles per charge, but itís a modestly appointed sub-compact car. The larger Tesla Model S can go further, but it costs 2 or 3 times as much as the Clarity Electric and its interior is decidedly more Spartan. At present, the Clarity Electric is available only in California and Oregon.

The 50-State Clarity is a Plug-In Hybrid

Image of Clarity Plug-In Hybrid logo

Honda decided to make a third version of the Clarity, the Clarity Plug-In Hybrid, instead of resurrecting the Accord Plug-In Hybrid (perhaps it would be too difficult to fit a 17 kWh battery into the Accord Hybrid). Unlike the its Clarity siblings, the Clarity Plug-In Hybrid includes an internal combustion engine (ICE). Also, Honda plans to sell the Plug-In Hybrid in all 50 states and Canada.

In September, 2017, Honda revealed the Clarity Plug-In Hybrid will have an all-electric range of 47 miles, only 6 miles less than that of the smaller Chevy Volt. On a 240-volt Level 2 charger, the Clarity Plug-In Hybrid requires only 2.5 hours for a full recharge versus about 4 hours for the Chevy Volt. Unlike the Clarity Electric, the Clarity Plug-In Hybrid cannot use a DC Fast Charger.
[Question: How long does the Clarity Plug-In Hybrid take to recharge on 110-volts?]

Disappointingly, the Clarity Plug-In Hybrid does not share the Clarity Electricís braking-regen control paddle. In my opinion, all rechargeable electric cars should provide a way for the driver to select any amount of braking regen. The new, second-generation, Nissan Leaf provides the best example of this capability. A Leaf driver can select braking regen so aggressive that "one-foot driving" is possible. With one-foot driving, the driver rarely needs to use the brake pedal. By simply lifting off the accelerator pedal, the driver can quickly slow the car to a complete stop while maximizing the regeneration of electric power.
[Question: Can a skillful driver fully recharge the Clarity Plug-In Hybridís battery?]

Photo of 2018 Clarity Plug-In Hybrid engine

The Clarity Plug-In Hybridís engine is a 1.5-liter 4-cylinder "hyper-efficient" Atkinson-cycle gasoline-powered mill, which is based on the 1.5-liter DOHC i-VTEC engine first used in the 2015 Honda Fit, according to Hondaís Natalie Kumaratne, Environment & Safety Public Relations. So the valves are driven by a long-lived timing chain instead of a worrisome timing belt. The naturally aspirated (ie. no turbocharger) Clarity engine can deliver up to 102 horsepower and 99 lb.-ft. of torque. Car and Driver provides a good explanation of the Atkinson combustion cycle and its benefits.
[Question: Are the air-conditioner compressor and the water pump both electric, making this a "belt-less" engine?]

Photo of 2014 Honda Accord i-MMD electric motors
i-MMD drive motor (left) and starter motor/generator (right)

The Clarity Plug-In Hybrid employs the two-motor Intelligent Multi Mode Drive (i-MMD) hybrid system Honda introduced with the 2014 Accord Hybrids. When powered by the battery only, the Clarity Plug-In Hybridís i-MMD electric drive motor can supply up to 121 hp. After the starter motor/generator starts the ICE and then switches to generator mode, the drive motor can supply up to 181 hp and 232 lb.-ft. of torque. Again, Car and Driver has the best explanation of Hondaís novel way of combining the output from an internal combustion engine with power from an electric motor.
[Question: What is the torque rating of the drive motor when operating only on battery power?]

Hondaís method for combining the output of an engine and a motor simultaneously offers benefits over a less-sophisticated plug-in hybrid that runs exclusively on battery power until the battery is discharged and then switches to its ICE to provide additional range (a "range-extender," as it were). The combined-power approach enables engineers to better optimize the sizes of both propulsive units. To provide the same acceleration as the Clarity Plug-In Hybrid, a hybrid that can use only one propulsive unit at a time would need both a larger electric motor and a larger ICE.

Hereís what normally happens as the Honda Clarity Plug-In Hybrid driverís right ankle is flexed:

  1. Depressing the accelerator pedal starts the car moving under power from the electric drive motor alone
  2. Continuing to press the accelerator provides up to 121 horsepower from the electric drive motor
  3. The accelerator pedal moves smoothly forward until greater resistance, a "detent," is felt
  4. Pressing harder moves the accelerator pedal through the detent
  5. The second electric motor (which is smaller than the drive motor) starts the ICE instantly
  6. After starting the ICE, the second electric motor becomes a generator powered by the ICE
  7. The generator and battery combine to power the drive motor up to its maximum of 181 hp and 232 lb.-ft.
  8. At some T.B.D. speed, the Clarity Plug-In Hybrid mechanically connects the ICE to the wheels
    [Question: Under exactly what circumstances does the mechanical ICE-to-wheels connection occur?]
    [Question: What circumstances terminate the mechanical ICE-to-wheels connection?]
    [Question: Is battery power used when the ICE-to-wheels connection is in effect?]
    [Question: Does the mechanical ICE-to-wheels connection happen in all modes and in the same way?]
  9. [Question: What is Hondaís name for the mechanical ICE-to-wheels connection?]
  10. At 100 mph, battery power is cut off and the car becomes just another speeding, gas-powered vehicle
    [Question: So the mechanical ICE-to-wheels connection must be in effect above 100 mph, right?]
    [Question: How can you get to 100 mph on battery power without triggering the mechanical connection?]
    [Question: How far can the Clarity Plug-In Hybrid go on 6.9 gallons of gas at 100 mph?]
    [Question: What is Hondaís name for ICE-only operation above 100 mph?]

Now Can I Avoid Gas Stations Forever?

Photo of Clarity Plug-In Hybrid recharging
Honda Clarity Plug-In Hybrid, plugged in

Honda reports the Clarity Plug-In Hybrid can achieve an EPA mileage rating of 44/40/42 mpg (city/highway/combined) when running only on gasoline. My last-century Honda Insight can easily top 70 mpg (using both ICE and battery power), but this tiny all-aluminum hybrid with its 0.9 kWh battery pack weighs about half as much as the mid-sized Clarity Plug-In Hybrid with its hefty 17 kWH battery pack. So it's not surprising that the larger, heavier car running without battery support would use more gas.
[Question: How heavy is the 17 kWH battery pack?]
[Question: How heavy are the two electric motors and support electronics?]

The EPA rates electric car efficiency in Miles-Per-Gallon equivalent (MPGe). The Clarity Plug-In Hybrid is rated at 110 MPGe when running on battery power.

Although my aging Insight achieves spectacular gas mileage, itís a one-trick pony. A Spartan, 2-seat, one-trick pony. The aim of Clarity Plug-In Hybrid is directed at a much broader target: to achieve environmental responsibility without compromising on comfort or "driveability."

Driveability is not a well-defined concept, but in my experience, Honda understands it very well. Thatís why Iím such a Honda fan-boy. Speed, handling, ergonomics, visibility, comfort, and even confidence in a carís reliability and safety all contribute to driveability.

Every car design involves compromises to achieve an overall goal. The ability to travel in the Clarity Plug-In Hybrid on battery power exclusively was in some situations a victim of the compromises required to maintain driveability. Consider these two requirements:

When the driver needs to go faster right now, it shouldnít be necessary to search for a mode button. Honda engineers came up with the accelerator pedal "detent" to give the driver access to maximum power without thinking about how to get it. Thatís driveability. The compromise is that the driver must exercise some right-ankle restraint in order to travel only on electric power—thereís no button for that.

The delivery of heat in cold weather is particularly important in a battery-powered car because it affects not only the carís occupants but also the carís batteries. Lithium-ion batteries donít do well in cold temperatures, so the Clarity cars all have systems to warm their batteries.
[Question: Does the Clarity Plug-In Hybrid warm the batteries with only electric power?]

Very, very cold temperatures can actually damage lithium-ion batteries, so the Clarity Electric is programmed to refuse to start when the temperature is below minus 22° Fahrenheit! Thatís decidedly not driveability, but the Clarity Electric isnít available in any state that suffers such extreme low temperatures.

Unlike the Clarity Electric and Fuel-Cell cars, the Clarity Plug-In Hybrid has an ICE to generate heat (hmmm, heat from ICE doesnít sound quite right, does it?). When the temperature dips to 14°F or below, the ICE starts up so it can warm the batteries.

To provide cabin heat while traveling on battery power when the ambient temperature is above 14°F, the Clarity Plug-In Hybrid provides resistive (electric) heating, as do its two ICE-less siblings. Of course, when you divert battery power to make heat, your all-electric mileage may vary—and not in a positive way. So the Clarity Plug-In Hybrid can alternatively pipe hot water from the ICE into the cabin to warm the occupants, but the ICE has to be running to make this water hot.
[Question: Does the mode selection determine which method of cabin heating is used?]

[Question: How does the air-conditioning system interact with the other systems?]

As noted in the list above, there are at least two other situations when the Clarity Plug-In Hybrid activates its ICE automatically: At certain higher speeds, the ICE is mechanically connected to gears that turn the front wheels. The other instance is when you want to go faster than 100 mph. At that speed, the Clarity Plug-In Hybrid cuts off all battery support, leaving the ICE all by its lonesome to soldier on in the pursuit of triple-digit speeds. Please donít expect the ICE to achieve 42 mpg at 100 mph.

So those are my speculations about about why the designers of the Clarity Plug-In Hybrid made compromises regarding all-electric operation. Perhaps weíll learn more about the priorities that influenced their decisions later. The Clarity Plug-In Hybrid wonít enable you to completely eliminate time-consuming trips to the gas station, but it can make those bothersome visits much more infrequent.

Different Modes for Different Driving Styles

As previously discussed, the Honda Clarity Plug-In Hybrid can use both gas and battery power at the same time. However, the car offers mode selections that allow the driver to prioritize one or the other.

Photo of 2018 Honda Clarity mode buttons

The Honda Clarity Plug-In Hybrid offers 3 modes that vary when the ICE kicks in to generate more electricity for acceleration. The three modes are Normal, Sport, and Econ. The Econ mode resists calling upon the ICE while the Sport mode is grateful for the assistance. Normal mode? Who would ever choose Normal? It doesnít even get its own button!

Thereís also a Hybrid Vehicle (HV) mode, which works in conjunction with the three previously mentioned modes. HV mode lets you use the ICE to conserve the charge in the battery pack for later use. For example, you could use HV mode to get from the country to the city, where youíd switch off HV mode and have many miles of non-polluting all-electric range remaining.

So to drive the Clarity Plug-In Hybrid running only on battery power, the driver can select Econ Mode and then avoid pressing the accelerator beyond the detent. Of course, the ICE will power the car after the battery is discharged, assuming the gas tank is not empty. To conserve the charge in the battery by driving primarily on ICE power, the driver can select HV Mode.

How Far Can This Car Go?

Photo of 2018 Honda Clarity Plug-In Hybrid range display
The bar-graph in the center indicates the state of charge of the battery

Speaking of range (and isnít that all anyone talks about when the subject is electric cars?), how far can the Clarity Plug-In Hybrid go on a full charge and a full tank of gas? Honda lists the maximum total range at 340 miles (in Econ mode, I assume). However, the above photo lifted from a review shows the HV range gauge indicating 343 miles, even with the battery having already powered the car for 32 miles. Curiously, in a car with a nominal range of 340 miles, the curved HV bar-graph displays up to a maximum of only 300 miles.
[Question: Do the HV Range bar-graph and digital read-out both represent gas+electric range?]

What? Only 340 miles?!? The nearly identically sized Accord Hybrid can go 758 miles on a tankful of gas and it gets only a few more miles per gallon than the Clarity Plug-In Hybrid. The limit on the total range of the Clarity Plug-In Hybrid is not only the size of its battery, but more importantly, the size of its gas tank.

Subtract the 47 miles of electric range from 340 miles and divide that 293 miles by 42 mpg and the gas tank capacity comes out to be less than 7 gallons!

Photo of Kegco 7-gallon jar
For Comparison Purposes Only

So why does the Clarity Plug-In Hybrid have a motorcycle-sized gas tank? To make room for the batteries without significantly reducing trunk space (see Clarity Electric) or eliminating fold-down rear seats (see Clarity Fuel-Cell). The Clarity Plug-In Hybridís trunk measures a sizeable 15.4 cubic feet. Behold the first Honda hybrid sedan to have fold-down rear seats:

Photo of 2018 Honda Clarity Plug-In Hybrid trunk
Honda Clarity Plug-In Hybrid trunk
(note trunk see-through window at top)

Look at it this way: While youíre tooling around town on battery power, youíre almost certain to be carrying the full tank of gasoline from your last visit to the gas station months ago, so the small gas tank reduces the weight of the gasoline youíre hauling around as you try to maximize your all-electric mileage.

On a long trip, you might choose to reverse the conventional idea of using the ICE as a "range-extender." Instead, you could start your trip with a fully-charged battery in HV mode to travel primarily on power from the ICE. Then, if there are no gas stations in sight when youíve reached the 293-mile limit of your 6.9-gallon gas tank, you will still have many miles worth of electric power to find more of that precious fossil fuel.

Which is the Better Hybrid, the Clarity or the Accord?

Your choice of a mid-sized hybrid comes down to time versus distance: If you want to go more than 750 miles between fill-ups, buy an Accord Hybrid. If youíre not a lonnng-distance commuter and want to potentially go months between bothersome, time-consuming, and potentially dangerous trips to the gas station, choose the Clarity Plug-In Hybrid.

One more thing: Plug-in electricity is cheaper than gas and all of the Accord Hybridís electricity comes indirectly from gas.

Note that some electric power companies offer lower off-hours rates for recharging electric cars. However, you'll have to install an additional meter and your company may have set limits on the number of homes that can select this option.

Clarity Plug-In Hybrid Features

Now that the unique nuts, bolts, and batteries have been covered, itís time to get to the goodies—the creature comforts and safety features built into the Clarity Plug-In Hybrid.

General Features

Safety Features

Exterior Features

Photo of 2018 Clarity Plug-In Hybrid key fob

Interior Features

Touring-Trim Exclusive Features

The 2018 Clarity Plug-In Hybrid, as an evolution of the 2017 Clarity Fuel-Cell car, does not include some of the latest Honda updates found in the 2018 Honda Accord. For example, the Clarity does not have the Accordís retro radio control knobs. Instead of the 2018 Accordís simple blind-spot warning system, the Clarity includes Hondaís older LaneWatch blind-spot video system from earlier Honda models. LaneWatch provides more information, but demands more involvement from the driver, who must focus on the dashboard video screen to evaluate the view from a camera mounted below the right rear-view mirror.

Hondaís list of Clarity Plug-In Hybrid features did not include the Clarity Fuel Cellís Head-Up Display or its Plasmacluster® Ion Technology for improving air quality. As previously regretted, the list also omitted the Clarity Electricís brake-regen control paddle.

Also, the Clarity Plug-In Hybrid does not include a rear cross-traffic alert, which has been available on other Honda models for years. However, the AAA warns drivers not to trust cross-traffic alert systems, suggesting itís better to back into a parallel parking place to make it easier and safer to leave.

Clarity Plug-In Hybrid Colors

The 6 Clarity Plug-In Hybrid exterior/interior color combinations are listed below (I hope I got the names right):

Below are images showing 5 of the 6 Clarity Plug-In Hybrid colors that have appeared on the web. I believe they are (from top to bottom) Moonlit Forest Pearl, Crimson Pearl, Platinum White Metallic, Solar Silver Metallic, and Modern Steel Metallic. For comparison purposes, Iíve included a photo of a Clarity Fuel Cell car in Crystal Black Pearl, which probably looks a lot like Crystal Black Metallic at this low resolution.

Photo of 2018 Honda Clarity Plug-In Hybrid in Moonlit Forest Pearl

Photo of 2018 Clarity Plug-In Hybrid in Crimson Pearl

Photo of 2018 Clarity Plug-In Hybrid in Platinum White Pearl

Photo of 2018 Clarity Plug-In Hybrid in Solar Silver Metallic

Photo of 2018 Clarity Plug-In Hybrid in Modern Steel Metallic

Photo of 2018 Clarity Fuel-Cell in Crystal Black Pearl

More Collected Images

Photo of 2018 Honda Clarity Plug-In Hybrid rear

Photo of 2018 Honda Clarity Plug-In Hybrid tail-light

Photo of 2018 Honda Clarity Plug-In Hybrid front quarter

Photo of 2018 Honda Clarity Plug-In Hybrid headlight

Photo ofHonda Clarity Plug-In Hybrid charge port access door

Photo of 2018 Honda Clarity Plug-In Hybrid driver's seat view

Photo of 2018 Honda Clarity Plug-In Hybrid gauges

Photo of 2018 Honda Clarity Plug-In Hybrid ceiling controls

Photo of 2018 Honda Clarity Plug-In Hybrid dashboard

Photo of 2018 Honda Clarity Plug-In Hybrid controls

Photo of 2018 Honda Clarity Plug-In Hybrid rear seats

Photo of 2018 Honda Clarity Plug-In Hybrid rear controls and power outlet

Photo of 2018 Honda Clarity Plug-In Hybrid view out rear

Photo of 2018 Honda Clarity Plug-In Hybrid non-Touring black interior

Photo of 2018 Clarity Plug-In Hybrid on the road

Photo of 2018 Clarity Plug-In Hybrid being recharged

Image of Clarity's body acoustics

Image of Clarity's straight frame components

Image of Clarity's use of high-tensile steel

Image of Clarity weight-reducing elements

Image of Clarity's body construction

Remaining Questions

Thank you for visiting my exhibition of the 2018 Honda Clarity Plug-In Hybrid!