Exterior Overview
When planning the current Accord Sedan, engineers were looking to put traditional Accord quality and reliability into a new package filled with more emotional appeal, and to employ sedan styling similar to popular luxury European sport sedans. The 2005 Accord Hybrid Sedan adds to this foundation design cues intended to help it achieve top-of-class fuel economy and to improve the car's aerodynamics and reduce its drag coefficient to a slippery 0.29. These additions include a rear decklid spoiler, lightweight 16" aluminum alloy aerodynamic wheels. Additionally, lightweight aluminum was used in the Accord Hybrid's hood, bumper frames and rear suspension knuckles, helping reduce overall weight.
Powertrain
In balancing the seemingly contradictory goals of high fuel efficiency and high performance, Honda combined the 3rd generation IMA system with the all-new Variable Cylinder Management (VCM) system that alone generates substantial fuel savings when full engine power is not needed (as in highway cruising and deceleration). Working together, the two systems provide exceptional fuel efficiency benefits when the engine is not at full capacity, but mid-sized class-leading power when the car is at full throttle. Overall, the VCM system helps to maximize highway fuel economy while the IMA system helps to maximize city fuel economy.
The engine used on the Honda Accord Hybrid Sedan is primarily the same as that of the Accord V-6, but with a few modifications to save weight and to allow for the use of Honda's VCM system. Foremost among these changes is the implementation of Honda's advanced i-VTEC system in place of the VTEC system of the Accord EX V-6.
Without any help from the electric IMA system, this 3.0L engine provides 240 hp and 217 lb.-ft of torque, but utilizes some lighter weight materials than the original version used in the standard Accord EX V-6.
First introduced to North America in the all-new 2005 Odyssey minivan, Honda's innovative Variable Cylinder Management (VCM) system has now been engineered to maximize fuel economy in the Accord's 3.0L i-VTEC V-6 in concert with the IMA system. It works by monitoring speed and throttle action to determine if full engine power is required, if not - as in steady cruising or minor acceleration, the rear bank of three cylinders is deactivated. Further efficiency is achieved when the fuel injection system cuts fuel to the three active cylinders when the car is decelerating or braking - a feature similarly employed in most Honda vehicles.
Additional efficiencies are gained by the use of lightweight magnesium for certain engine parts, and the Accord Hybrid Sedan's engine incorporates a new engine head to manage the VCM system. A new airflow sensor and a 2-axis belt drive with an auto tensioner help to maintain maximum efficiency and prevent power losses due to friction.
IMA technology
The 3rd generation of Honda's Integrated Motor Assist system - which incorporates an ultra-thin electric motor (68mm) mounted between the gasoline engine and automatic transmission - is the largest and most efficient Honda has produced. The motor produces 10 percent more horsepower assist (12 kW total) than the Civic Hybrid and 26 percent more supplemental torque (100.4 lb.-ft. total). During regenerative braking when the motor acts as a generator for the IMA's battery pack, the generator also produces 12% percent more kW of power (14 kW total), and in both cases, the motor is more efficient, transferring 97.5 percent (vs. 94.6% in Civic Hybrid) of the available energy in assist mode, and converting 95.2 percent (vs. 93.6%) of renewable kinetic energy into electrical energy in charge mode. In addition, the Accord Hybrid's Nickel Metal-Hydride battery pack and integrated cooling system are more compact, yet more efficient than that in a Civic Hybrid Sedan.
Transmission
A specially modified version of the existing 5-speed automatic transmission was specified for the Accord Hybrid Sedan. This new transmission is more compact than that in an Accord EX V-6 Sedan and is specially designed to work with the IMA's electric motor to maximize the motor's ability to regenerate electricity during regenerative braking.
The transmission uses a high response lockup clutch torque converter for improved fuel efficiency while an integrated electric oil pump helps provide smooth and quick restarts of the engine after idle stops. With a slightly wider range of gear ratios than the automatic transmission in an Accord EX V-6, acceleration is quick from the line and the taller 5th gear helps conserve fuel during highway cruising.
IMA Operation
Though drivers will notice a different experience when it comes to the reduced frequency of fuel stops, the actual driving experience is virtually identical to that of a traditional Accord EX V-6. The complex processes that make the Accord Hybrid the fuel efficient car that it is would go unnoticed if not for the small IMA display integrated into the car's speedometer.
At startup, the Accord Hybrid's engine runs at idle speed until the driver increases the throttle to begin accelerating. During acceleration, all six cylinders of the Accord Hybrid's 3.0-liter engine are active, with the IMA system helping if hard acceleration is required. If this is the case, the blue indicator bars in the Accord's IMA display will light to show that the IMA is in Assist Mode.
When the driver minimizes accelerator input at cruising speed, a number of fuel saving operations begin. First, the Variable Cylinder Management (VCM) system can deactivate the engine's rear bank of three cylinders to effectively cut fuel consumption in half. At the same time, the IMA's Intelligent Power Unit turns the IMA motor into a generator to begin regenerative braking and the IMA display's green bars illuminate to show the level of electrical energy being created. If, during cruising, power is required to maintain speed, the IMA motor will offer assist while the rear cylinders remain inactive.
As the vehicle begins to slow and the driver applies the brakes, more electricity
is created through regenerative braking and the VCM system cuts fuel to the
active front bank of three cylinders to further conserve fuel.
As the driver continues to apply the brake, the IMA system can completely idle-stop
the engine when vehicle speed drops below 8 mph. An indicator in the instrument
panel's tachometer flashes to alert the driver that the car is idle-stopped.
When the driver releases the brake pedal, the IMA motor instantaneously spins
the engine back into action with all six cylinders firing at idle speed. Occasionally,
the idle stop feature is disabled when driving on a hot day and full air-conditioning
power is needed by the hybrid air conditioning system. At all other times, idle
stop can be activated once the vehicle speed exceeds approximately 10 mph.
Chassis Overview
The suspension and steering set up for the Accord Hybrid Sedan is essentially the same as that of the existing Accord EX V-6, except for the adoption of electric power steering (EPS) versus a traditional hydraulic power rack and pinion steering set up in the Accord EX V-6.
The 7th-generation Accord's 4-wheel double wishbone suspension continues to be one of the most sophisticated arrangements in the mid-sized sedan class. The front double wishbone suspension ensures accurate tracking at all vehicle speeds, while the rear 5-link double wishbone suspension mounted to the car's subframe helps to limit body roll during cornering and also isolates the cabin from road noise.
Electric Power Steering also contributes to higher fuel economy (engine power is not needed to pump the hydraulic system). While similar to the performance-oriented steering systems used in the Honda S2000 and the Acura NSX, the high-mounted EPS system in the Accord Hybrid is designed to provide complete steering operation during idle stop mode.
The Accord Hybrid Sedan also employs a similar braking system as to that of
the Accord EX
V-6, which includes ventilated discs in the front and solid discs in the back.
Braking is further enhanced by a standard 3-channel anti-lock braking system
(ABS) and electronic brake distribution (EBD). Accord Hybrid has wider 215/60
R16 tires compared to those on the EX
V-6 Sedan.
Interior Overview
Continuing Honda's strategy of incorporating hybrid technology seamlessly into its mainstream vehicles, there are few interior differences between Accord Hybrid and an Accord EX V-6 Sedan. The main differences are the unique instrument panel meter display that shows the IMA system's charge and assist status, IMA battery charge levels, "ECO" light indicating VCM operation, along with trip and lifetime fuel economy readouts. Less obvious, but much more significant is Active Noise Control (ANC) - which helps to reduce the engine booming sound inherently created inside any engine that has cylinder deactivation, and a new hybrid air conditioning unit that is powered by a combination of the gasoline engine's drive belt and a supplemental electric motor depending upon cooling needs.
The Active Noise Control uses microphones in the front and rear of the passenger cabin to monitor the low-frequency "booming" noise created by three-cylinder engine operations. It then generates a counter-cycled sound wave through the car's audio system that effectively cancels the booming noise.
The hybrid air conditioning unit uses two air compressors, one connected to the gasoline engine and one connected to an electric motor. When full cooling is needed, as when a car is first started on a hot summer day, the HVAC control unit relies on both to create maximum cooling power. Under normal conditions, cooling is provided by either the belt-driven compressor attached to the 3.0-liter V-6 or the electric magnet driven compressor powered by the IMA battery. This allows the air conditioning system to work at virtually all times, even when the car is at idle-stop.
The Accord Hybrid Sedan features a standard leather-trimmed interior with heated front seats, an AM/FM/XM audio system with 6-disc in-dash CD changer, dual-zone automatic climate control, power windows, mirrors and door locks and a HomeLink remote system. The only factory option on the Accord Hybrid Sedan is the Honda Satellite-linked Navigation System with voice recognition.
Safety Overview
The Accord Hybrid Sedan retains all of the Accord's class-leading safety technology, including dual-stage, dual-threshold front airbags, dual front side airbags and side-curtain airbags to protect front and rear passengers in the unlikely event of a rollover impact.
In addition to the advanced passive safety technology of the Accord Hybrid Sedan, it also utilizes the same active systems as all Accord V-6 sedans. This includes four-wheel disc brakes with a three-channel anti-lock braking system, electronic brake distribution, and a 2nd-generation traction control system (TCS).
New with the Accord Hybrid Sedan is the car's Instant Mobility System,
which replaces a traditional spare tire with a flat tire repair kit. The elimination
of a spare tire provides an extra covered storage compartment within the car's
trunk. The Accord's IMS provides a convenient and quick process to repair
most flat tire situations.
Retail Gas Prices in the United States (August 6, 2001 to Present)
After a brief decline in prices at the end of 2001, retail gasoline prices have
been rising steadily to a peak of 2.02 per gallon of regular (87 Octane), unformulated
unleaded gasoline during the 2004 Memorial Day weekend. This is even more profound
in states like California, where emissions regulations require further refinement
of the gasoline sold. In California, the reformulated regular unleaded gasoline
is currently going for $2.19 per gallon after reaching a peak of 2.33. Though
the gas shortage of the mid-1970's was more substantial on an inflation-corrected
basis, this is the first time in the history of the United States that gasoline
prices have topped $2.00 nationwide.
At current prices in California, using an average of 15,000 miles driven in a year, Accord Hybrid Sedan drivers would reduce their fuel expense over $350 per year compared to a traditional Accord EX V-6 ($997/year vs. $1,369)*.
* 33 combined mpg (Hybrid) vs. 24 mpg (Accord V-6). SOURCE: US Department of Energy