On the 2017 Honda Accord Hybrid

For model year 2014 Honda came out with a two-motor hybrid system for the Accord. For model year 2017 Honda went back at the system and provided improvements to what was already a segment-leading system.

Koji Ninomiya has spent much of his career at Honda working on Accords. As the large project leader for the 2014 Accord Hybrid, his depth of knowledge of what was then a benchmark vehicle is profound. And so he and his team had to work even harder to best what was already class-leading. The ninth generation Accord sedan, upon which the Hybrid is based, is, like Accords throughout its history, often thought of in the context of its quality, durability and reliability (QDR). Yet Ninomiya says that the "grand theme" for the development of the 2017 Accord Hybrid contained three key words, none of which sound even faintly like those of QDR.

Rather, they are: Fun. Advanced. Environment. The last first.

Obviously, the whole purpose of having a hybrid powertrain is to achieve greater fuel efficiency. Yet hybrids have been on the market for a sufficiently long time such that efficiency has to come with performance.

Honda has been in the hybrid space for quite a while, with the Insight on the market in the U.S. in 1999 (which even beat the Toyota Prius in the U.S. market). Honda had an Accord hybrid model available in the U.S. from model year 2005 to 2007, then released a new hybrid architecture, the two-motor design, in model year 2014. But that car had limited availability for a number of reasons, and it disappeared from the market for a year, to be replaced by the 2017 Accord Hybrid, a hybrid that offers a new take on the two-motor hybrid system and which will, Jeff Conrad, senior vice president and general manager of Honda Division, believes have double the annual sales of the previous model (there were 14,000 of that car; Conrad says that by building the cars in a plant in Sayama, Japan, rather than in the U.S., there will be greater availability).

So one of the ways that “Fun” is being realized in the 2017 model is increasing the overall horsepower of the system by 16, to 212 hp.

That said, this is still a hybrid and fuel economy still matters, so that has been improved, as well. Based on the new EPA fuel economy calculation methodology for 2017 vehicles, the Accord Hybrid has ratings of 49 mpg city, 47 mpg highway and 48 mpg combined. While those numbers don’t look as good as the numbers for the 2014 Accord Hybrid, it turns out that were that car to be tested under the new regime its numbers would have been 48/45/47 mpg rather than the 50/45/47 mpg that the car was stickered at.

According to Honda the 2017 Accord Hybrid bests its model year 2017 segment competitors including the Ford Fusion Hybrid, the Hyundai Sonata Hybrid and the Camry Hybrid.

Putting that horsepower to use in terms of “Fun” resulted in changes to the steering and suspension of the Accord, such as deploying high-performance amplitude reactive dampers as well as putting new operation logic into the electric power steering system (called “Angular Velocity Feedback”) that helps provide precise, stable and quick response as needed, depending on whether one is going down a straightaway or wending through curves.

While in some regards the “Advanced” could be simply the connectivity that the Accord Hybrid offers—as in Apple CarPlay and Android Auto—as well as the Honda Sensing Suite, which is based on a suite of sensors and algorithms for functions ranging from not only keeping in one’s lane but on the road itself, another way to consider “Advanced” is in the context of the powertrain system that leads to the other point on Ninomiya’s list, “Environment.”

The system—the second generation version—is called the “Intelligent Multi-Mode Drive,” or simply i-MMD. This is a two-motor setup that works in concert with the 143-hp, 2.0-liter, DOHC i-VTEC Atkinson Cycle in-line four, based on the direction of the power control unit (PCU).

The vehicle can accelerate from a stop under electric power, using the electric propulsion motor to power the front wheels, with the gasoline engine decoupled from the drivetrain to minimize parasitic losses from friction. The system is designed so that the gasoline engine can act as a generator—this is done via the second motor in the two-motor system, a generator motor that is linked to the engine—that provides electrical energy to the propulsion motor to charge the lithium-ion battery. This is a “series hybrid” approach.

The Accord Hybrid also operates as a “parallel hybrid” when the engine sends power directly to the drive wheels, supplemented, as needed, by the electric propulsion motor. When cruising at mid- to high-speeds, a lockup clutch engages to connect the drive motor and the generator motor to efficiently transmit engine torque to the wheels.

The 2017 Accord Hybrid doesn’t have a mechanical transmission (nor a torque converter). Rather, the operations of the gasoline engine and the two motors are coordinated based on driving needs.

Compared to the 2014 model, the motors are smaller and lighter (on the order of 23 percent) and yet have greater performance, based, in part, on the use of three smaller, lighter magnets (rather than two larger ones) and square copper wire instead of round wire, which results in a denser, more compact stator. The propulsion motor is rated at 181 hp and 232 lb-ft of torque, which are improvements of 14.8 hp and 6 lb-ft, respectively. The generator motor is up 1.2 hp to 142 hp; its torque is the same as the previous generation, at 62.7 lb-ft.

Smaller and lighter is a theme throughout the powertrain system. The PCU is 23 percent smaller and 27 percent lighter than the previous. The intelligent power unit (IPU), which combines a DC-DC converter and 1.3-kWh lithium-ion battery pack, is 33 percent smaller and 12.8 percent lighter. The size reduction is important because the IPU is packaged behind the rear seat, so by going smaller, there is an increase of 0.8-ft3 in the trunk. The mass reduction is, of course, important in terms of overall vehicle performance: the new IPU weighs 99.2 pounds.

Honda is committed to alternative powertrains. The Clarity fuel-powered vehicle is expected to launch before 2016 is out and a plug-in Clarity and an electric Clarity are scheduled for 2017.

According to Conrad, by 2030 up to two-thirds of Honda’s global sales will consist of “electrified vehicles,” and he emphasizes that this is electrification beyond stop-start systems.