While "IMA" refers to the Insight's hybrid powertrain as a whole, the various parts that comprise IMA are spread throughout the car. The gasoline engine, as you would expect, is located under the hood. What Honda calls the Intelligent Power Unit (IPU) is located under the rear cargo floor. Anyone who has ever seen the original Insight's high, impractical rear cargo floor can understand how much smaller the IPU is now than it was nine years ago, because the 2009 Insight's cargo floor is as low and easily accessible as it is in any conventional hatchback car, including the Honda Fit. In any event, the IPU consists of a battery pack; a power control unit; and a cooling system that sucks air in from the cabin, routes it through the IPU and around the back of the car, and then ejects it into the left rear wheel well. The whole IPU is no larger than a modestly sized desktop printer.
As for the nickel-metal-hydride batteries, there are seven modules of them, each containing twelve D-size cells, for a total of 84. By comparison, the Civic Hybrid's IPU contains eleven modules, but the Insight's batteries are some 30 percent more efficient than those in the Civic. According to Honda, they are also 30 percent more durable. Fewer batteries helps lower both cost and weight; the Insight's IPU is 28 percent lighter than the Civic's.
Despite vast improvements in the efficiency of the IMA system over time, the new Insight falls short of the fantastic fuel economy numbers - 61 mpg city, 70 mpg highway - of its parsimonious predecessor. However, when those figures are recalculated using the EPA's latest methodologies, they are reduced to a more realistic 49 city, 61 highway, 53 combined. For the new Insight, Honda wagers that 40 city, 43 highway (41 combined) will be enough to lure customers who also are attracted to the car's affordability and practicality. It seems like an effective compromise and, if anything, these figures, not yet ratified by the EPA as we went to press, will be easy to beat. More on that shortly.
Current Honda owners who get behind the wheel of the new Insight will feel instantly at home. The cabin design and ambience are an appealing mixture of Civic, Fit, and first-generation Insight, with effective ergonomics, intuitive controls (the radio interface is especially nice), and lots of nooks and crannies for storage. One of the things you give up at this price point over the Civic Hybrid is the ability to pay extra for leather upholstery, and you'll be reminded of this every time you run your fingertips over the cheap seat fabric. (Another sacrifice is stability control, available only on the EX.) As for the seats themselves, the fronts are simple and comfortable, while the outboard rear seats offer good headroom, decent legroom, and good footroom. The middle rear seat is high, flat, and hard and is a miserable place to spend more than two minutes - it's difficult to imagine three people sharing the rear row unless they're all preteens. The rear seatbacks fold easily although not completely flat. The cargo area is top-notch, with a big exterior opening through the hatch, a low lift-over height, a tall load space, and a broad, flat floor.