Sierra Mazda’s Guide to Green Driving: Part 10
Ken Liu’s Hybrid Discussion Part 1
The 2008 Honda Civic Hybrid. The current generation Honda Civic Hybrid is the fourth iteration of Honda’s Hybrid system. Its genealogy consists of the Honda Insight, the 2003-2005 Honda Civic Hybrid, the 2005-2007 Honda Accord V6 Hybrid. During those generations Honda learned a great deal and has applied these lessons to the latest technology in today’s Honda Civic Hybrid. So what’s changed compared to the previous generation? Mainly a higher capacity battery and a more efficient electric motor/generator.
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A brief background on how Honda’s hybrid system works. Honda’s hybrid system consists of a thin electric motor/generator that is sandwiched between the gasoline engine and the transmission. It measures roughly 3 inches wide. The transmission is more compact to retain about the same drive train dimensions as a “regular” Civic. How does the electric motor/generator work? To better illustrate how the system operates, picture yourself when you were young learning how to ride a bicycle. When you were pedaling and your parent pushed you to gain momentum, you did less work to achieve a greater speed and acceleration. Your parent “assisted” you in increasing your speed. That’s how Honda’s hybrid system works. The electric motor “pushes” the gasoline engine to achieve better acceleration at lower speeds thus requiring less fuel. The main propulsion of the Civic Hybrid is its gasoline engine. The electric motor assists it when the computer system deems necessary. This is why Honda calls its hybrid system the IMA (Integrated Motor Assist). It’s a very elegant and simple solution.
A little background on electric motors. Unlike gasoline motors, which must spin several THOUSAND RPMS to achieve maximum torque, the electric motor achieves maximum torque at 0 RPMS. The strength of the electric motor is that it allows Honda to use a smaller engine than its Civic siblings (1.3 ltr vs 1.8-2.0 ltr). In a gasoline engine, a larger motor will produce more torque, but the trade-off is greater fuel consumption. Once up to speed the car needs very little power to maintain its velocity. Honda’s goal is to use an engine as small as possible to maximize fuel efficiency. The smaller engine works great at highway speeds, but will hinder its off-the-line acceleration. This is where the electric motor comes into play. The electric motor helps the acceleration to about 35 mph, afterwards the gasoline motor has enough pull to work on its own. Once up to speed, the 1.3 liter has enough power to accelerate comfortably on the highway while consuming very little fuel. As a result of its engine size, the Civic Hybrid is able to achieve an EPA estimated 45 mpg on the highway, and a very impressive EPA estimated 40 mpg in the city by the EPA. These are, of course, estimates and the real results depend on the many of the considerations we have discussed in our green guide, including the driver.
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