Honda Insight -- Body and Interior
Honda engineers knew that the Insight's body would play a major role in help-ing 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.
The Insight's aluminum body in white (just the sheet metal: doors, hood, etc.) is roughly 40 percent lighter than a comparable steel body.
HONDA INSIGHT EXTERIOR FEATURES
- World-class aerodynamic body design
- Light-alloy wheels with aerodynamic covers
- P165/65R14 low-rolling-resistance mud- and snow-rated tires
- Dual body-colored mirrors
- Body-colored door handles
- Intermittent windshield wipers
- Rear window wiper/washer
- Halogen headlights
- Roof-mounted radio antenna
- Integrated, high-mounted brakelight
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.
AERODYNAMIC TECHNOLOGIES USED IN THE HONDA INSIGHT
- One of the lowest coefficients of drag (0.25) of any mass-produced automobile in the world
- Aerodynamically shaped nose, windshield and windshield posts
- Flat floor and underbody
- Tapered body with 4.3-inch narrower track at the rear wheels
- Low-drag door mirrors
- Low height, small frontal area and long, tapered roofline
- Strakes at the side- and rear-lower edges of the Insight's body help to minimize aero drag by controlling underbody airflow
- Aerodynamic rear-fender skirts and disc-shaped alloy wheels smooth airflow around the wheel openings
- The engine air inlet louvers are shaped to efficiently admit cooling air
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 wheelwells 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 wheelwell is inset and faired into the body. Disc-shaped aluminum wheels also help smooth airflow around the wheelwells.
The importance of minimizing air turbulence at the rear of the vehicle is also evident in the Insight's design. Since a teardrop shape disturbs airflow around a moving body the least, the rear of the Insight narrows and tapers in cross-section. Even the rear-wheel track is narrower than the front, by 4.3 inches. The rear wheels also sit in enclosed fairings. Special aerodynamic skirts further smooth the airflow around the wheel openings.
At the very back of the Insight, the teardrop shape is abruptly cut off in what is called a Kamm back (a distinctive design feature also shared by the Honda CRX). The Kamm back takes advantage of the fact that beyond a certain point there is little aerodynamic advantage to be gained by rounding off or tapering and extending the tail section of an automobile, so one might as well abruptly truncate it at that point. The Kamm back is a design feature that has been incorporated into many high-performance automobiles and racing cars over the years.
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.
In order to minimize air leakage to the underside, the lower edges of the sides and the rear of the body form a strake that functions as an air dam. At the rear, the floor pan rises at a five-degree angle toward the rear bumper, creating a gradual increase in underbody area that smoothly feeds underbody air into the low-pressure area at the rear of the vehicle.
ALUMINUM BODY CONSTRUCTION
In city driving, much of a vehicle's power is consumed accelerating and decelerating. A lighter vehicle requires less energy to accomplish this, so Honda engineers specified aluminum alloy as the material of choice for the Insight. With the exception of its plastic front fenders, rear fender skirt and trim pieces, all of the Insight's major body panels are made from this lightweight alloy As a result, the Insight body is 40 percent lighter than a comparable steel body, such as the Civic Hatchback, yet it possesses 13 percent greater bending rigidity and 38 percent more torsional rigidity.
From their experience building the Acura NSX -- the world's most produced aluminum-bodied car -- Honda engineers have gained extensive knowledge of aluminum. However, the Insight is designed for a very different purpose.
Market requirements dictated the development of new, more cost-effective techniques for manufacturing the Insight's aluminum body. In response to this challenge, Honda engineers developed the Insight's innovative unit-body/space-frame construction.
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 wheelwells, 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.
On the Insight, each frame member's size and strength is optimized so that the frame is strong where it needs to be, and lighter in less critical areas. A variety of shapes are used, including hexagons, ovals, H-sections and reinforced box-sections. The door and windshield pillars, front and rear side-frame members, lower body sills, crossmembers and floor frame members are all formed in this manner.
In more highly loaded areas of the body (such as the front and rear subframes), larger, internally ribbed, hexagonal aluminum frame members are used. These are joined to other frame members via rigid, die-cast aluminum joints. Die-castings are also used at engine and suspension mounting points. These die-castings offer versatility and cost savings, because they can be designed to suit specific size, space and strength requirements.
THIXOTROPHIC DIE CASTING
Some of the die-cast joints used in the Insight's aluminum body are made using a newly developed casting technology invented by Honda engineers, called Thixotropic Die Casting. Thixotropic Die Casting uses aluminum alloy that has been heated to a semi-solid condition, instead of the molten, liquid state normally used in die casting. Pieces made with molten aluminum must be more highly processed and refined before casting; however, Thixotropic Die Casting requires less energy for smelting (an important consideration since aluminum is more expensive than steel), and owes much of its strength to the controlled formation of discrete aluminum crystals within the metal casting.
G-FORCE CONTROL TECHNOLOGY
The Insight's aluminum body and frame are designed to meet the safety and impact-protection standards Honda engineers set for it. At the heart of this design is a newly developed Honda technology called C-Force Control Technology, or C-CON. G-CON optimizes each part of the Insight's aluminum body and frame to best absorb a specific type of impact. The cabin floor, for example, forms a strong and rigid foundation, designed to minimize deformation in an impact. Outside of this area, the surrounding aluminum frame members have been tailored to control impact forces.
Full-frontal and offset-frontal impacts are first absorbed by the large-section, hexagonal extrusions that serve as the front-side frame members. These hexagonal sections are made up of six individual equilateral triangles and are designed to progressively collapse like the bellows of an accordion in an impact. A die-cast aluminum joint connected to the rear of these extrusions transfers any additional impact energy rearward to an oval-shaped, curved hexagonal extrusion, which further absorbs energy by bending upward.
The aluminum extrusions that extend from the passenger compartment all the way back to the rear of the Insight on either side are also designed to progressively absorb rear-impact energy. In addition, the spare tire and wheel, and the Insight's aluminum suspension, including the tires and wheels, are designed to aid in rear-impact energy absorption.
Cabin deformation in a side impact is minimized by the Insight's highly rigid aluminum side pillar, side sill, rigid floor frame, floor crossmember and side-impact beams built into the doors.
Of particular note is the fact that Honda conducted impact testing on the Insight at higher speeds than that required to pass U.S., Japanese and European certifi-cation. Full frontal tests were conducted at 35 mph, offset-frontal tests at 40 mph, and side and rear tests were conducted at 31 mph.
HONDA INSIGHT INTERIOR
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.
HONDA INSIGHT INTERIOR FEATURES
- Electric power steering system (EPS)
- Dual front airbags (SRS)
- Power windows with auto-down driver's window
- Power door locks with remote keyless entry
- AM/FM stereo cassette player with clock
- Electronic InstrumentDisplay
- Fuel-mileage computer
- Economy shift indicators
- Available automatic air conditioning
- Heat-rejecting, green-tinted glass
- 2-speed/intermittent windshield wipers
- Rear window defroster
- 3-spoke sport steering wheel
- Reclining high-back bucket seats
- Driver's storage compartment
- Lockable glove compartment
- Passenger seatback pocket
- Remote fuel-filler door release
- Driver's footrest
- Rear-center net pocket
- Hidden storage compartment
- Cargo area hooks
- Cargo area light
- Driver's vanity mirror
- Headlights-on reminder
- Map lights
- 12-volt accessory outlet
- 3-point seat belts with pretensioners and load limiter
INTERIOR LAYOUT AND DESIGN
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.
ELECTRONIC INSTRUMENT DISPLAY
Housed in a hooded central pod directly in front of the driver, the Insight's Electronic Instrument Display is a combination analog and digital readout that shows all important information about the Insight's Integrated Motor Assist (IMA) system and its effect on vehicle performance.
The display is divided into three sections. On the left is the gasoline-engine status section, showing engine rpm and coolant temperature, as segmented analog displays. In the middle of the IMA display is a large digital speedometer, and below it is the Insight's lifetime odometer. Along with the lifetime odometer, a lifetime fuel-economy readout and a bar graph that. shows instantaneous fuel economy from 0 to 150 miles-per-gallon can be displayed.
A button on the left side of the instrument panel, marked "FCD" for fuel-consumption display, toggles between the lifetime odometer, two resettable trip odometers and a third mode called the trip-segment mileage display. The two trip odometers, marked A and B, also show trip fuel economy, as well as instan-taneous fuel economy. The trip-mileage display mode can be used to ascertain a miles-per-gallon reading for a specific segment of a trip, such as freeway fuel economy or fuel economy while accelerating.
The right side of the Insight's Electronic Instrument Display houses IMA system indicators for fuel level and battery charge, and the IMA Charge and Assist indicator. The Charge and Assist indicator shows whether the IMA system is being recharged or is supplying electrical energy to the IMA electric motor. An economy shift-indicator with arrows for both up and down shift points, is located in the center of the display.
The usual warning and status lights for various systems, such as the Immobilzer Theft-Deterrent system, SRS, door and hatch ajar, electric power steering and electrical system are also part of the Electronic Instrument Display.
AUTOMATIC AIR CONDITIONING
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.
INSIGHT INTERIOR SAFETY FEATURES
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.
STORAGE AND CARGO
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.
The 5.0-cubic-foot cargo area is situated directly behind the driver's and passenger's seats, and is easily accessible through the rear hatch. An additional 1.5-cubic-foot, hidden storage compartment is built into the floor of the cargo area. The Insight's space-saver spare tire is located in an easily accessible com-partment under the cargo area floor. The IMA Power Control Unit (PCU) and the nickel-metal hydride battery pack are also housed under the cargo compartment floor in an electrically and physically isolated compartment and are protected in rear impacts by the rear suspension.