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Show Time for the New 2006 Civic Hybrid IMA: More Power and More Efficiency

The 2006 Civic Hybrid

Honda is rolling out its fourth-generation IMA (Intelligent Motor Assist) hybrid powertrain in the 2006 Civic Hybrid (earlier post), to be on display at the Frankfurt motor show.

Compared to the 2005 Civic Hybrid, the 2006 model with the new IMA is 18% more powerful than its predecessor while delivering a combined EPA estimated fuel economy of 50 mpg US compared to 47–48 mpg US of the 2005 hybrid. The new IMA also adds the ability to cruise only under the power of the electric motor.

The new 2006 Hybrid delivers 110 hp (82 kW) and 123 lb-ft (167 Nm) torque with 50 mpg US.

The fourth generation Honda IMA system consists of a 93-hp 1.3-liter i-VTEC 4-cylinder engine connected to a 20-hp electric motor and a Continuously Variable Transmission (CVT). Combined, the powertrain delivers 110 hp (82 kW) and 123 lb-ft (167 Nm)of torque.

A 158-volt, 5.5-Ah Nickel-Metal Hydride (NiMH) battery captures and stores electricity from regenerative braking for the electric motor.

The 2006 Civic hybrid powertrain has four basic modes of operation that are applied in different driving scenarios:

  1. Engine off. This is when the vehicle is stationary, but powered on. The engine is turned off and fuel consumption is zero. The battery powers electric systems (including air conditioning).

  2. Low-speed valve timing (LO-VT). The engine operates in low-speed valve timing mode, sometimes assisted by the electric motor. The Civic applies this mode for startup and acceleration with motor assist, and with engine-only operation for high-speed cruising and gentle acceleration at higher speeds.

  3. High-speed valve timing (HI-VT). This mode is for rapid acceleration at higher speeds, and has the engine operating in high-speed valve timing mode with motor assist.

  4. Cylinder Idle. The valves of all four of the engine’s cylinders are closed and combustion halted. The electric motor alone powers the vehicle. This is also the mode for deceleration, where the motor recovers a significant portion of the energy normally lost during deceleration and stores it in the battery.

The different modes of the 2006 Civic Hybrid IMA under appropriate operating conditions.

Engine Valve/Cylinder Management, Ignition and Fuel Injection.. The Civic Hybrid uses a 3-Stage i-VTEC valve control system that provides the different valve timings (high and low) and the cylinder idling functions. The previous generation system in the 2005 Civic Hybrid uses 2-stage VTEC that provides normal valve timing and 3-cylinder idling. The new 3-stage system adds high output valve timing and full-engine 4-cylinder idling.

The high output valve timing contributes to the engines increase in output of 9%, while the added cylinder deactivation reduces pumping losses by 66% to help improve electrical regeneration capability by 1.7 times.

The Civic Hybrid’s single overhead camshaft (SOHC) cylinder head uses a compact chain drive and a compact, low friction VTEC system. It uses a common rocker shaft for both the intake and exhaust rocker arms. Placing all the rocker arms on one shaft eliminates the need for a second rocker-arm shaft, so the valve mechanism can be lighter and more compact. To reduce friction, the rocker arms have rollers built-in.

The compact valvetrain allows for a narrow 30º angle between the intake and exhaust valves, which helps supply a more powerful direct charge into the cylinder chamber. The narrow angle valvetrain also allows for a more compact combustion chamber. The intake ports create a swirl effect in the cylinder chamber that promote a well balanced and even air fuel mixture as it enters the engine. This optimizes the air fuel mixture for a cleaner, more efficient combustion.

The new VCM (Variable Cylinder Management) system is an advanced form of the three-cylinder Cylinder Idling System used on the previous generation. VCM allows the regenerative braking system to reclaim as much energy as possible during deceleration, while also allowing the electric motor to propel the vehicle in certain steady state cruising situations.

Since the electric motor, which also acts as an electric generator, is attached directly to the crankshaft of the engine, the engine needs to provide as little resistance as possible during deceleration to allow the generator to produce high levels of electricity and charge the batteries. In a traditional engine, the pumping action of the cylinders will actually provide a moderate amount of resistance, or engine braking, during deceleration. VCM virtually eliminates that effect.

The 3-stage VTEC valve switching capabilities are enabled by three hydraulic circuits in the rocker arm.

From a mechanical standpoint, the 3-stage VTEC switching capabilities are made possible by a rocker arm design with three hydraulic circuits that accommodates:

  • low-rpm VTEC switching on each cylinder’s intake and exhaust valve

  • high speed switching on the [intake] valve

Three oil passages inside the rocker shaft receive oil from an external spool valve (controlled by the ECU based mostly on throttle and rpm). The oil pressure from one of the three passages activates a combination of push pins inside the rocker arms for each of the intake and exhaust valves. By moving the pins, the intake valve rocker arms can follow one of two lobes on the camshaft (normal or high profile). Or, to deactivate the valves and leave them closed, the pins are pushed in a direction that allow part of the intake and exhaust rocker arms to move with the camshaft and not move the closed valves.

Each cylinder in the iVTEC engine has twin sparkplugs for sequential ignition control. The ignition control has eight ignition coils that are independently controlled according to a dynamic engine map program. The benefits are more power, less fuel consumption and reduced emissions.

When the air/fuel mixture enters the combustion chamber, the first plug located near the intake port ignites. Shortly thereafter, the second plug located near the exhaust port ignites, accelerating the combustion process by forcing the flame to more rapidly propagate. The spark plugs can also ignite simultaneously under certain circumstances. This process results in a more complete combustion compared to a single plug system.

The Civic Hybrid is also equipped with a Programmed Fuel Injection (PGM-FI) system. The system monitors throttle position, engine temperature, intake-manifold pressure, atmospheric pressure, exhaust-gas oxygen content, and intake-air temperature. It controls fuel delivery by multi-holed injectors mounted in the plastic intake manifold. The ECU also tracks the operation of the engine with position sensors on the crankshaft and camshaft.

The Electric Motor. The ultra-thin (70 mm) DC brushless electric motor is mounted between the gasoline engine and the continuously variable transmission and provides up to 15 kW (20 hp) and 66 lb-ft of additional torque to the engine. An Intelligent Power Unit (IPU) that stores electric power in a compact battery box and controls the flow of electricity to and from the electric motor is in the rear of the car.

A new internal permanent magnet increases output density and makes the motor more efficient than previous motors. It also uses flat wire construction to increase wire density. The electric motor has increased output horsepower by 50 percent and maximum torque by 14 percent compared with the 2005 Civic Hybrid IMA motor. The electric motor is also more efficient, now converting 96% (versus 94.6% efficiency of the 2005 Civic Hybrid IMA motor) of the available electricity into motive energy in assist mode.

Energy Storage and Management: the IPU. Located directly behind the rear seatback, the IPU consists of the Power Control Unit (PCU), a rechargeable Nickel Metal-Hydride battery module, and an integrated cooling unit.

The PCU’s response time is quickened over previous versions, and a new inverter and DC/DC Converter help contribute to the IMA's overall increase in peak power.

The battery pack stores electricity in a bank of Nickel Metal-Hydride cells. This bank of 132 1.2-volt units stores up to 158 volts of electrical energy for the IMA motor compared to 144 in previous versions. A new Panasonic dual module casing reduces weight from previous hybrid battery packs and also allows it to increase efficiency of the electrical flow. The battery pack is also 12% smaller in volume than the prior.

The Integrated Cooling Unit offsets the heat generated by the constant flow of electricity to and from the battery pack with an integrated cooling system mounted directly on the battery pack’s outer box. Interior cabin air is continually flowed over the battery pack and re-circulated via a small vent placed on the rear seat shelf.

Regenerative Braking. New for 2006, a cooperative regenerative braking system debuts on the Civic Hybrid with the added capability to intelligently proportion braking power between the hydraulic brakes and the electric motor to extract even more electricity from the vehicle’s kinetic energy. Less reliance on the traditional braking system and reduced engine pumping losses translate into greater electrical regeneration (170% more than the 2005 Civic Hybrid) and ultimately improved fuel economy.

When braking, a brake pedal sensor sends a signal to the vehicle's IMA computer (IPU). The computer activates a servo unit in the brake system’s master cylinder that proportions braking power between the traditional hydraulic brakes and the electric motor to maximize regeneration. Previous versions of Honda’s IMA systems proportioned braking power at a pre-set rate below the maximum regeneration threshold and with no variable proportioning.

The Continuously Variable Transmission. Honda’s fourth generation of Continuously Variable Transmission (CVT) is standard equipment on the Civic Hybrid and provides a 9% wider range between the maximum and minimum gear ratios to enhance acceleration and minimize engine rpm at high speeds. The transmission provides smooth and predictable transitions and helps keep the IMA system operating at its peak efficiency.

Honda Civic Hybrid 2006 vs. 2005
Vehicle Type Sedan Sedan Same
Wheelbase (in.) 106.3 103.1 +3.2
Length (in.) 176.7 175.4 +1.3
Width (in.) 68.9 67.5 +1.4
Height (in.) 56.5 56.3 -0.2
Engine 1.3-liter i-VTEC SOHC 1.3-liter VTEC SOHC + i-VTEC
Electric Motor hp @ rpm 20 @ 2000 13 @ 4000 + 7
Cylinder Deactivation 4-cylinder 3-cylinder Full Engine Deactivation
Power 110 hp (82 kW) 93 hp (69 kW) +17 hp (+13 kW)
Torque Nm @rpm 167 @ 1000-2500 142 @ 3000 (CVT) + 25 @ - 500
Transmission CVT CVT or MT CVT standard
Tire Size P195/65 15 P185/70 15 Larger tire
Fuel Economy city/hwy mpg 50 / 50 47 / 48 (CVT AT-PZEV) + 3 / +2
Weight 2875 2740 + 135
Emissions AT-PZEV (50 State) AT-PZEV (CA +) 50-State AT-PZEV
Passenger Volume (cu. ft.) 90.9 91.4 -0.5
Front/Rear Leg Room (in.) 42.2 / 34.6 42.2 / 36.0 0/-1.4
Front Hip Room (in.) 51.8 / 51.0 51.3/ 49.8 +0.5/+1.2

The 2006 Civic is incrementally larger, definitely more powerful but still more efficient than its predecessor. It’s good to see a new hybrid platform rolled out that leans more toward the efficiency end of the scale rather than the performance hybrids of late.

Honda’s market timing is impeccable. It will be very interesting to see how rapid the uptake is on this car, given the surge in sales of the current Civic hybrid last month. (Earlier post.)



Nice try -- I'm sure that a few years from now we will all look back and laugh at a wopping 50 miles per gallon - we'll laugh because plug in hybirds will be getting 500 mpg for an average comuter that goes any where rom 20 to 60 miles a day. I know the research says people don't want to plug them in but at $5 or $6 a gallon or more it seems like such a small thing to do. Besides the research never asked the question -- If you could get 500 mpg would you mind taking a few moments (seconds) out of your day and plugging in your vehicle??


I don't think it's the plug that's the issue, it's the batteries. Present day hybrids can only go a few miles on their batteries. To make a plug in hybrid practical, it needs enough batteries to cover a substantial part of the trip. Those batteries are what add all the expense that makes the PUH impractical today.


Excellence job to Honda - we are slowly replacing part of our engine to electric motor. I believe in a few decades we will all look back and laugh at all internal combustion cars. The target is to make an EV that go 300 miles for a 3 minutes charge. Plug in at home is absolutely easier then going to gas station for a refuel. We can even have regenerative battery power, like just letting your car sit under the sun for a while and you get your baby charged.

Harvey D

John is right. Hybrids, PHEVs et EVs will evolve quickly specially if the price of fuel keeps going up and if we are serious about reducing air pollution. The cost of better batteries wil certainly go down quick during the next 3 or 4 years. A Chinese company recently found a way to cut the cost of primary (not rechargeable) lithium batteries by 10 to 30 times. The next step will probably be a similar cost reduction for the secondary batteries (rechargeables). That would make PHEVs and Evs much more affordable and competitive. Unfortunately, most low cost high performance rechargeable battery packs for vehicles will be manufactured in Asia where more plentiful labour, at a much lower cost, is available.


My hat is off to Honda to slowly get us off fossil fuels. But what good is, even the best hybrid, if gas is far too expensive to obtain? America is being slowly drained of our life blood until we slip into unconcious and die.
We must reject fossil fuel transportion solutions.
Save it for tires and plastics that at least we can partially recycle. We must do it now


I don't think range is the issue it once was. PHEV's or all-electrics (like the Colt EV, I believe) can go about 100 miles on batteries, which is fine for a high percentage of daily commutes.

Once gas starts to get expensive in the US (over $5/gallon), then I think consumers will be begging car makers for PHEV's and all-electrics. It will be interesting to see which companies realize this is coming and start working on them now, so they can jump on the opportunity relatively quickly. I have a hunch Toyota has a complete (or nearly so) plan for a PHEV Prius just sitting in their back pocket. Probably the same goes for Honda and the Civic Hybrid.


Tony, all of us are in the same boat, we normal consumer can do nothing but just let the big oils to slowly drain our life line away. The entire modern human civilisation is build up on top of fossil fuel. Take that away and we are worse then what we are 200 years ago. Dont really think that we can now grab our suitcase and jump up on a horse and go to work. The good thing is the world wont be running out of gas overnight, but it will get more and more expensive, and therefore making alternative fuels a feasible way to go(and therefore big oils willing to invest $$). And then there we will have E85, B100 or NGV(natural or bio gas) or FT syndiesel... blah

Btw, instead to get a full size hybird, getting a cheap compact diesel car is also a way to go. You can easily chew up to 60 mpg.


Rexis, I am not talking about a "horse" solution, but I would like to see a national goal of all cars and trucks of 8,000gvw or less be fossil and emissions free by 2016.
California tried to do it but wimped out. This is how we got the first EV cars from the big auto makers. President Bush needs to champion this. No one else has the clout or Karl Rove to pull it off.
Otherwise, if a real major fossil intreuption occurs, America will be wiped out. Everyone knew it was coming!! But our (local and federal)leaders failed us in long term planning. Just like New Orleans, Everyone knew it was coming!.
Frankly, I have now accepted that us humans don't fix problems until a disaster occurs.. and sometimes it takes a second disaster.
I love diesels and the new technology too. In fact, I owned an Olds diesel for ten years and a Chevy Diesel van for 14 years. But now with the ever increasing price
fuel and the 15 to 20% more for diesel, they no longer make sense.
And finally we must face the moral consequences for our lust for oil. Going to war to control the dwindling supply of oil.


Indeed, 'horse' solution is no solution. Sad to know that war is one of the solutions. Pity them who can only sit there seeing a disaster apporaching them while their leaders going holiday or shopping. There are always one million and one other better ways to solve the same problem, but yet, it is the one who in charge make the big final decision. When the bad decisions finally bring in real consequences, the person in charge will be no longer in charge, and someone else will worry about that.


100% EV vehicles, given our present energy infrastructure would cause more pollution than hybrids.
Remember that most of our electricty (in the US) still comes from Coal. Also don't forget that Honda intends to have a hydrogen fuel cell car commercially available for ~$30k by 2015.

100% EV vehicles won't help emissions overall w/o entirely revamping the electricity infrastructure. (At least in the US, I can't speak for other nations :) )

ALso... I REALLY hope that Honda adds simular improvments to the Insight, for the last week I've been getting nearly 100mpg in mine, the improvments of this IMA system could significantly improve the Insight's MPG (and performance)




It's not quite as simple as you suggest, for the following reasons:

1. Peak demand is currently during the day, but most recharging would occur at night using spare capacity. Is that spare capacity unused coal, nat'l gas, or what? Without knowing that detail, it's impossible to know if the plug-in hybrid charge would be 50% from coal, more, or less.
2. The marginal cost to build another coal plant is pretty constant, except that people don't like coal power plants in their backyard. So, the coal plants are having a tough time building more, and paying a bit more to do so.
3. When we get electrical meters that are "connected to the Internet" we can have the price of electricity be a function of the availability of renewable resources -- that is, when the wind is blowing, the price of electricity becomes cheaper. Why is this important? Well, if your car needed 6 hours to charge and had 12 hours to do it, you could electronically control the charging so that it only occurred when the electricity prices were cheapest -- when green-e was available. As a result, the value of wind energy to society would increase, and we'd be substituting fossil fuels for wind energy more and more often.

It will all take time, and be done incrementally. Each of us can do our part by participating in the changeovers. Buy a hybrid. Try not to consume electricity during peak load (often 3-6pm). Reduce your consumption in general. Buy green-e credits. Make sure you are amoung the "best" 10% when it comes to fossil fuel consumption. Then, help others join you in that 10% through technical advice, advocacy, political lobbying, whatever.

Mikhail Capone

Quite glad that Honda decided that ULEV wasn't good enough and made the 2006 Civic hybrid and Accord hybrid AT-PZEV.


Hydrogen ICE vehicles are ready to go they hybrid vehicles or regular ICE vehicles. Fuel cell vehicles can follow later. If you want a quick short term fix...get the automotives to produce hydrogen ICE vehicles and then couple that with Honda's home energy station to produce hydrogen in your home.

John W.

has anyone heard the speed ranges that the all electric mode for the new civic runs in? Up to 20 miles per hour? 30? And what the range for battery only is? I haven't heard that information released from Honda yet. And I'm not sure if they're on the road yet.

I love Honda, but they need to lose some of their corporate pride--that is, regarding their prowess with the 4-stroke engine, which made them so famous in the first place. (They don't seem to want to relinquish the priority of their ICE's.) They can work magic with a gas engine, true, but it's (internal combustion engine) days are somewhat numbered now, and if they would only make their cars say, 50-50 electric/gas, or at least use much more electricity, they would be much more efficient, esp if plug in and you can charge it with your own solar panel battery bank! (Esp. if they could use a much smaller version of their European Diesel instead of the four-stroke). Here's hoping they'll take the plunge sooner than later.

G. Man

BUSH, ROVE? HAHHAAHHAHAHAHAA... Please tell me you were joking! We'll NEVER see good energy policy from a man who is so tied to oil that when he sneezes, he creates an oil slick in his tissue. It would be nice, for once, if people actually voted/supported political candidates based on their views on IMPORTANT generational issues instead of voting along party lines. Sheesh, no wonder we're heading the way of the Roman Empire...our days are numbered I'm afraid.

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