Text below is lifted from Wikipedia

History
Based on the Honda J-VX concept car unveiled at the 1997 Tokyo Motor Show, the Insight was introduced in 1999 and was the first production vehicle to feature Honda’s Integrated Motor Assist system. The Insight was also the first hybrid sold in North America. It featured optimized aerodynamics and a lightweight aluminum structure to maximize fuel efficiency and minimize emissions.

Total global sales for the Insight amounted to only around 18,000.

Design
The Honda Insight was a subcompact hatchback 3,945 mm (155.3 in) in length with a wheelbase of 2,400 mm (94.5 in) a height of 1,355 mm (53.3 in) and a width of 1,695 mm (66.7 in). The Insight was only available as a two-seater. Only three different trims were available: a manual transmission without air-conditioning, a manual transmission with air-conditioning, and a continuously variable transmission with air-conditioning. Although produced until 2006, the only major change was the introduction of a trunk mounted, front controlled, multiple CD changer.
One key in increasing the vehicle’s fuel efficiency was reducing the mass via the extensive use of aluminum and plastic. Honda built the insight with aluminum front brake calipers and rear brake drums; the fuel tank was plastic; the engine mounts were aluminum; and the exhaust was a small, thin wall pipe. The Insight weighed 1,847 lb (838 kg) in manual transmission form or 1,964 lb (891 kg) with CVT and air conditioning. The combination of materials and design gave the Insight body structure 13 percent more bending strength and 38 percent more torsional rigidity than a comparably-sized steel body, despite weighing 40 percent less.
The New York Times wrote that the Insight’s styling “suggested Popeye’s pal, Olive Oyl, in her ankle-length dress. The rear fender skirts seemed frumpy.”

Technology
The gasoline engine is a 70 hp (52 kW; 71 PS), 1-liter, 3-cylinder unit providing lean burn operation with an air fuel ratio that can reach 25.8 to 1. The electrical motor assist adds in another 10 kW (13 hp) when called on, and similarly provides significant deceleration when used in regenerative mode for braking. (This both improves fuel efficiency and also dramatically extends the lifetime of brakes). When the car is not moving, for example, at a stop light, the engine shuts off. The digital displays on the dashboard display fuel consumption instantaneously. On the manual transmission up and down arrows suggest when to shift gears. The Insight uses the first generation of Honda’s Integrated Motor Assist (IMA) hybrid technology. (The next generation, used in the Honda Civic Hybrid, is much more space-efficient.) The Insight has a 3-cylinder 1.0 L (61 cu in) engine and a brushless 10-kW electric motor located on the crankshaft. Located behind the seats are a series of commercial grade “D” sized NiMH batteries wired to provide a nominal 144 V DC. During heavy acceleration, up to 100 Amps are pulled from the NiMH batteries, the electric motor provides additional power; during deceleration, the motor acts as a generator and recharges the batteries using a process called regenerative braking, charging them with up to 50 Amps of current. A computer control module regulates how much power comes from the internal combustion engine, and how much from the electric motor; in the CVT variant, it also finds the optimal gear ratio. Dashboard gauges monitor the current battery, instantaneous fuel consumption and mode of the electric motor — standby, engine assist or charging the batteries.
High pressure, low rolling resistance tires and the use of low viscosity “0w-20″ synthetic oil both enhance fuel economy.
The original Insight had a conventional manual transmission. Starting with the 2001 model, a CVT variant of the Insight was available; the CVT is similar to that used in the Honda Civic Hybrid and the Honda Logo. A feature shared by the two hybrids (and now appearing in others) is the ability to automatically turn off the engine when the vehicle is at a stop (and restart it upon movement). Since it is more powerful than most starters of conventional cars, the Insight’s electric motor can start the engine nearly instantaneously.
The Integrated Motor Assist is run by an “Intelligent Power Unit (IPU)”, a desktop computer-sized box. The Intelligent Power Unit, the Power control Unit, the Electronic Control Unit, the vehicle’s batteries, converter and a high-voltage inverter are all located under the cargo floor of the vehicle, behind the seats.
To maximize fuel efficiency, the Insight was very aerodynamic. The Insight had one of the lowest coefficients of drag of any marketed automobile giving it a coefficient of 0.25.
The Insight was available with a manual transmission or a continuously variable transmission (CVT). A traditional transmission shifts between a fixed set of engine-to-wheel ratios; however, a CVT allows for an infinite set of ratios between its lowest gear and its highest. The CVT-equipped Insight was classified as a super-low emissions vehicle.
The Insight features low emissions: the California Air Resources Board gave the 5-speed model a ULEV rating, and the CVT model earned a SULEV rating. (The 5-speed’s lean-burn ability is a trade-off which increases efficiency at the expense of slightly higher NOx emissions.)