The Honda Insight equipped with the innovative Integrated Motor Assist (IMA) was the first gasoline-electric hybrid automobile to be sold in USA. IMA couples an all-new and compact 61 cui, 3-cylinder engine and an ultra-thin electric motor for outstanding efficiency. That combined with a rigid aluminum body structure and world-class aerodynamic design gives the Insight the ability to travel as far as 70 miles on a gallon of gasoline and still meet California’s stringent Ultra-Low Emission Vehicle (ULEV) standard, making it the world’s cleanest, most fuel-efficient gasoline-powered automobile.
Honda has traditionally believed that cars should operate in harmony with their environment and society. This credo has prompted continuous research and product development in the field of low-emission, high-mileage vehicles over the past 30 years. One of the first results of this work was the Honda CVCC Civic, launched in 1975. It had a special Compound Vortex Controlled Combustion that allowed it to meet the new emissions regulations of the time, without the need for a catalytic converter. In 1985 the Honda 1.3-liter CRX HF was the first "high-mileage" Honda, followed by the 1992 Honda Civic VX, with its lean-burn, VTEC-E engine. Moreover, in 1996 Honda introduced the Civic HX Coupe featuring a VTEC-E engine and highly efficient continuously variable transmission that made it the first automobile equipped with an automatic transmission to make it into the EPA’s top ten list.
After having decided on using a hybrid gasoline-electric propulsion system for the Insight, the first step in its development was to identify a set of performance goals for the car. The main goal was that of achieving the highest fuel economy possible. Honda engineers set as a target 70-plus miles per gallon and above. Ultra-low emissions were an equally important engineering goal, as well as safety and performance. Honda engineers wanted the Insight to have a level of performance comparable to that of a 1.5-liter engine automobile. Finally, the Insight, like all Hondas, would have to be durable, reliable and built to Honda standards of quality, comfort and drivability.
The Insight drives just like any other automobile. Its range is limited only by its 10.6-gallon gas tank. No external power supply is needed for recharging. It is a full-featured automobile, backed by the Honda reputation for durability, quality and reliability.
At the heart of the IMA system is a compact, 61 cui, 3-cylinder gasoline automobile engine. The engine uses advanced lean-burn VTEC-E technology, low-friction design features and lightweight materials such as aluminum, magnesium and special plastics, in combination with a new lean-bum-compatible NOx catalyst, to achieve a new level of efficiency and low emissions in gasoline-engine technology.
The electric component of the IMA system consists of an ultra-thin, 2.3-inch wide permanent-magnet electric motor operating in parallel with the gasoline engine. Electricity for the motor is stored in a 144-volt nickel-metal hydride battery pack and controlled via an advanced electronic Power Control Unit (PCU).Unlike a pure battery-powered electric vehicle, the Insight does not require an outside source of electric power. Electricity for the system is generated primarily by regenerative braking.
In addition to being light, the Insight’s futuristic-looking aluminum body is also highly aerodynamic in both its shape and details, and boasts one of the lowest coefficients of drag (0.25) of any mass-produced automobile sold worldwide.
Body & chassis
Honda engineers knew that the Insight’s body would play a major role in helping it achieve the fuel economy, performance and safety goals they had set for it. In response to this challenge, they came up with an innovative, new body design for the Insight that is lightweight, rigid and highly aerodynamic.
Since a lightweight vehicle has better performance and fuel economy than a heavier one, the Insight’s body is made from aluminum alloy. Aluminum weighs only one-third as much as steel. In addition, aluminum alloy is highly versatile and readily lends itself to a wide variety of manufacturing techniques. Lastly, aluminum is extensively recycled, which helps lower its cost.
At highway speeds, the airflow around a vehicle becomes turbulent. Turbulent air generates considerably more drag than smooth-flowing (laminar) air. In addition, as speed increases, the power required to overcome turbulence-induced drag rises exponentially. To combat the effects of drag, Honda engineers designed the Insight’s body to be highly aerodynamic. Its 0.25 coefficient of drag (Cd) is one of the lowest of any mass-produced automobile in the world. In comparison, the Honda Civic Hatchback, with roughly the same 1.9 square-meter frontal area as the Insight, has a Cd of 0.36, and needs around 32 percent more power to operate at the same speed as the Insight.
The Insight’s futuristic, aerodynamic shape is both distinctive and functional. The low, rounded nose is designed to part the air with a minimum of turbulence, and also affords the driver and passenger an unobstructed forward view. Louvers in the cooling-air inlets have been carefully designed to minimize turbulence. The headlight assemblies blend smoothly into the contour of the fender, and the fenders have large-radius curves in order, to minimally disturb the air flowing around them.
To minimize frontal area and drag, the windshield is steeply raked, and its edges blend smoothly with the sides and cabin roof. The trailing edge of the hood and cowl are shaped to smoothly divert airflow over the windshield wipers.
The roof tapers to the rear of the vehicle in a teardrop shape. The cabin’s ample glass area affords good outward visibility in all directions, and also lends a light, airy feeling to the interior. The glass rear hatch has an additional panel that lets the driver see what is immediately behind the vehicle - an especially useful feature when backing up.
The Insight’s gently curved sides and wheel wells are also designed to minimize air turbulence. The plastic-resin front fenders extend downward below the centerline of the wheel and incorporate a small air dam in front of the wheel. To further minimize turbulence, the trailing edge of the wheel well is inset and faired into the body. Disc-shaped aluminum wheels also help smooth airflow around the wheel wells.
Another important aerodynamic detail that greatly contributes to the Insight body’s low coefficient of drag is the careful management of underbody airflow. The Insight body features a flat underbody design that smoothes airflow under the car. Areas of the underside that must remain open to the air, such as the exhaust system and the area around the fuel tank, have separate fairings to smooth the airflow around them.
Design goals for the Insight’s chassis centered around achieving sporty and responsive handling, good ride characteristics and world-class safety, all while contributing to the overall goal of reaching the highest fuel efficiency possible. To meet this challenge, Honda engineers developed an innovative new chassis design that takes advantage of the high strength-to-weight properties of aluminum and plastic.
The unit-body part of the Insight’s body uses stressed sheet-metal panels to absorb and distribute structural and suspension loads, much like an ordinary steel unit body. However, with the Insight’s body all of these panels, including the roof, floor, front and rear wheel wells, rear quarter-panels, bulkhead, and even the doors and hood, are made of aluminum alloy. These stressed panels are reinforced in key areas by aluminum-alloy frame members.
It is these aluminum frame members and their cast-aluminum connecting joints that make the Insight’s hybrid body so unique. In a steel unit body, frame members are formed by stamping in large presses and then joined to the body by welding. However, the Insight uses extruded frame members. Extrusions are drawn from a die in much the same way that tubing is made, and like tubing are of constant cross section. Once formed, extrusions can be easily made into complex three-dimensional pieces, such as a curved windshield frame. They also do not require any additional machining or finishing after they are formed.
The Insight’s IMA system owes much of its remarkable performance to the application of numerous technologies developed by Honda over the past four decades, including lean-bum combustion, low-emission engines, variable valve timing, high-efficiency electric motors, regenerative braking, nickel-metal hydride battery technology and microprocessor control. In the IMA system, Honda engineers have optimized the performance of each of these technologies to create an efficient, lightweight and compact hybrid drive system that people can easily use and that does not require any changes in lifestyle. Here’s how it works:
Primary motive power for the Insight is provided by the system’s 61 cui, 12-valve, 3-cylinder, VTEC-E gasoline engine. Although the engine alone provides sufficient driving performance, even in sustained uphill driving, a permanent-magnet electric motor mounted between the engine and transmission provides power assistance under certain conditions, such as initial acceleration from a stop. In addition, since the electric motor is used only for power assistance and not for primary motive power, it too can be made smaller and lighter relative to the full-size traction motors in other hybrid systems.
As the IMA gasoline engine enters it’s mid to high rpm operating range, the electric motor assist ceases and power is solely supplied by the engine, which is operating in its high-rpm 4-valve mode.
Power for the electric motor comes mainly by recapturing energy from the forward momentum and braking of the vehicle, rather than from the gasoline engine. When the Insight is coasting or its brakes are applied, and the vehicle is in gear, its electric-assist motor becomes a generator, converting forward momentum into electrical energy, instead of wasting it as heat during conventional braking (vented front disc/rear drum brakes are still the main means of braking). If the charge state of the IMA battery is low, the motor/generator will also recharge while the Insight is cruising, however, the advantage of regenerative braking is that it eliminates the need for a large, on-board electrical generating system, like the ones used on most parallel hybrid gasoline-electric drive-trains.
This beneficial spiral of decreasing weight, reduced size and complexity and increased performance continues with the IMA nickel-metal hydride battery pack (a technology Honda pioneered in its EV PLUS electric car), which is also smaller and lighter in weight than the ones used in other hybrid systems. The batteries are located under the cargo compartment floor, along with the IMA system’s Power Control Unit (PCU).
Compared to a comparable internal-combustion-powered drive-train, like that in a Honda Civic, the Insight’s IMA system boasts an impressive 24-percent improvement in efficiency in combined-mode city and highway driving, while meeting California’s stringent Ultra-Low Emission Vehicle (ULEV) standard.
Some of the advanced technologies used in the Insight’s IMA gasoline engine include its compact VTEC-E cylinder head, nitrogen-oxide adsorptive catalytic converter, integrated cylinder head and exhaust manifold, and plastic-resin intake manifold, valve cover and water-pump pulley. Magnesium alloy is used to make the oil pan, and the IMA engine also boasts numerous advanced friction-reduction techniques that help minimize frictional power loss.
Fuel induction is via an advanced version of Honda’s sequential programmed fuel injection, and the ignition is a direct type with individual ignition coils for each cylinder and long-lasting iridium-tipped spark plugs.
Honda engineers designed a completely new 5-speed manual transmission for the Insight. Like the rest of the Insight, its new transmission is designed to be as lightweight and as compact as possible, and is sized to the power requirements of the IMA system. The new transmission weights just 91 pounds and is 9.25 pounds lighter and almost a half an inch shorter than the current Civic manual transmission.
In order to minimize power loss within the transmission, the gears have been carefully machined to reduce rotational mass. The transmission’s lubricating system has also been redesigned to provide more efficient lubrication with a smaller oil capacity, thereby saving additional weight and size.
The transmission’s shift linkage operates smoothly, with minimal effort, thanks to the use of shortened synchronizer sleeves and a redesigned reverse-gear mechanism. A neutral switch built into the transmission tells the IMA idle-stop feature when the transmission is in neutral.
The Insight’s front independent suspension uses a strut-type spring/damper unit at each wheel. To save weight, the strut’s damper rod is hollow. Additional unsprung weight is saved by the use of a lightweight forged-aluminum steering knuckle and a forged-aluminum lower suspension arm. The system is also very compact - both of the lower arm’s inner pickup points are connected to the same reinforced, cast-aluminum mounting. The wheel is also a lightweight aluminum casting. An O.66-in.-diameter stabilizer bar links the front wheels. The front suspension geometry has been optimized to exhibit mini-mal changes in toe and camber throughout its travel, giving the Insight responsive handling, excellent stability and a smooth ride.
The Insight’s rear suspension consists of twin trailing arms interconnected by a curved, flattened beam (called a twist beam) midway along their length. The twist beam is open along one side, so it will twist in response to the movement of the trailing arms and function as an anti-roll bar (stabilizer bar). The Insight’s twist-beam rear suspension system is very compact, and, along with a 10.6-gallon, plastic-resin fuel tank and spare-tire compartment, sits entirely below the cargo area floor. Coil springs are used, and the system’s telescopic shock absorbers are mounted at a separate location, which also contributes to the Insight’s flat cargo floor.
Large rubber bushings, built into the trailing-arm pivots, provide bump compliance, as well as enhanced stability via toe control when cornering. The trailing arms and interconnecting twist beam are made of steel.
In the interest of reducing overall vehicle weight, Honda engineers specified front brake calipers and rear brake drums made of aluminum (these components are usually made of iron). Like the rest of the suspension’s aluminum components, these lightweight pieces also help to enhance vehicle handling and ride quality.
Front Brakes: Power-Assisted Ventilated Disc (9.1 in.)
The Honda Insight uses an innovative high-mounted rack-and-pinion steering system, assisted by an electric motor, called EPS (Electric Power Steering). EPS offers numerous advantages over conventional hydraulically assisted steering systems: it is simpler and more compact (there is no need for a hydraulic pump and hoses), and the power loss is minimized. The system’s compactness and simplicity offer more design freedom in terms of placement within the chassis, and it is also smoother operating, more responsive to driver input, and has minimal steering kickback. The overall steering ratio is 16.4 to 1, and 3.32 turns lock-to-lock.
Tires & wheels
The Insight features specially designed 165/65 R14 78S mud- and snow-rated low-rolling-resistance tires, mounted on 14 X 5.5 jj aluminum-alloy wheels. These new tires have 40 percent less rolling resistance than conventional tires and a 5-percent reduction in weight.
The Insight’s interior is intended to function as what Honda calls a "personal-fit capsule." A comfortable, relaxing personal space for the driver, with a modern, high-tech and sporty feel that further enhances the car’s personal, sporty character.
The seating and control layout in the Insight reflects its sporty nature. Outward visibility, sightlines and control placement are designed to enhance driver concentration and ease of movement. Honda designers have also designed the Insight’s interior to be comfortable and relaxing. The high-backed bucket seats are highly supportive to help minimize fatigue during long periods of driving.
The interior is fully carpeted and upholstered, and a variety of patterns and textures are used to create a high-tech but comfortable look. The instrument panel has a two-tone, black-and-gray finish.
Controls for the power windows and mirrors and the heating, ventilation and available automatic air conditioning system (HVAC) are all within easy reach. The controls for the AM/FM stereo cassette are set just below the driver’s panel for easy access, and individual driver’s and passenger’s map lights and the interior light are conveniently located overhead. The driver’s sun visor also features a vanity mirror. The door inserts are fabric-upholstered and incorporate armrests, passenger-assist grips, speakers and power door-lock controls. The padded, three-spoke steering wheel is the same design used on the Honda S2000 sports car.
The Insight’s optional automatic air-conditioning system can maintain the same cabin temperature year-round. A special feature of the system is its large, easy-to-use, electrically operated controls, conveniently located to the right of the IMA display. Three face-level vents are located directly in front of the driver, and a single vent is located in front of the passenger. A micron air-filtration system is standard.
Numerous storage areas are conveniently located throughout the Insight’s interior, including a driver’s storage compartment, a pullout change-storage tray in the instrument panel, two beverage holders in the center console and a 274-cubic-inch glove compartment, located in the instrument panel directly in front of the passenger seat. Additional storage in the passenger compartment includes a passenger seatback pocket and a handy rear-center net pocket.
Safety features in the Insight passenger compartment include dual airbags (SRS), 3-point seat belts with pretensioners and load limiters, and fixed head restraints. The interior is also designed to help protect its passengers from side impact and head injury.
TheHonda Insight is a very original and intensely refined automobile. It had as a goal in development an extreme reduction in fuel consumption and everything in this car converges to that purpose. It is not exactly a beautiful car, but the extreme aerodynamic performance can excuse that. The technical aspects of the Insight are delicate issues, and therefore hard to tweak, we tried to improve looks without affecting the much the technical side. First of all, we changed the front bumper with one adapted form the latest Honda S2000, that has a more aggressive look and is as aerodynamic. We added a double scoop on the right side of the hood to help cool the engine and, also break up the monotony of the bonnet. The highly developed tires of the Insight with their low rolling resistance abilities are not something to mess with. So, we let them as they are, but we did change the goofy original wheels with a set of 14” Yokohama 10 spokes. We further recommend a green metallic paint, to clearly state the ecological abilities of the car.