How the Honda Civic Hybrid Works

Models present the new Honda Civic Hybrid car at its launch in Kuala Lumpur, Malaysia, on March 19, 2009.
Models present the new Honda Civic Hybrid car at its launch in Kuala Lumpur, Malaysia, on March 19, 2009.
AP Photo/Vincent Thian

The streets in downtown Los Angeles, Calif., bustle with activity -- especially on a Friday afternoon. People try desperately to beat the traffic to get out of the city, only to cause, well, more traffic. On any given Friday afternoon, any large city like L.A. can be confused for a day after Thanksgiving stampede at a Best Buy.

Imagine, for a moment, that you're one of these frantic commuters. You use the subway to get in and out of the city and, for the most part, it works well for you. You don't have to worry about traffic; you just have to navigate through the streets on foot until you get to your train station. In fact, you routinely dodge past taxi cabs and time your movements through streets full of moving cars as if you're part of one big, well-oiled machine. As you approach the corner in which the entrance to your train station lies, you have just one more busy street to cross. Once you're in the zone, you move with cat-like precision. Just one more street, and then suddenly -- a reality check.

Within one lane of your final curb, you dive out of the way of a horn-blowing Honda Civic as its screeches to a halt about 10 feet (3 meters) past where you were just standing. Lucky for you, it missed. You never heard the car coming -- it's like it appeared out of nowhere. You wonder, have your senses of sight and hearing failed you? Suddenly you realize that you did see it, but you thought it was parked -- and you never actually heard it. In reality, the Honda Civic that just about creamed you was running. Well, sort of. You see, it's a Honda Civic Hybrid. And like magic, the engine in a hybrid Honda Civic only runs when it needs to.

For the most part, hybrid vehicles don't stray too far away from the typical everyday car. Nevertheless they are unique in some ways. The most glaring differences come in the form of the electrical components. On the next page, you'll learn Honda's secret behind its hybrid success. You'll also figure out why you were almost run down while crossing that busy street. Turn the page to meet Honda's Integrated Motor Assist (IMA) system.

The Honda Civic Hybrid System

The Honda Civic Hybrid features a 1.3-liter i-VTEC gasoline engine and a 20 horsepower electric motor.
The Honda Civic Hybrid features a 1.3-liter i-VTEC gasoline engine and a 20 horsepower electric motor.

If ever two automotive concepts were made to come together, the Honda Civic and hybrid technology are it -- a perfect match. Honda built the first Civic in 1972 to compete with the growing number of American subcompact cars that were designed and built in response to the growing concern of increasing gas prices. The first generation Civic managed between 40 and 45 miles per gallon (17 and 19.1 kilometers per liter) depending on driving conditions.

Over the next 20 years, Honda built a reputation as a fuel-efficient auto manufacturer. Every vehicle featured small, high-revving engines that were extremely efficient and reliable. It's a reputation that continues to hold true today.

To date, Honda has maintained its commitment to small engines. No production vehicle including those built domestically or in Japan feature an engine with more than six cylinders and a displacement over 4.0 liters. When Honda decided to merge its hybrid technology into an existing passenger car, the obvious choice was the Civic. In 2004, Honda made the leap. By taking a standard Civic and mating it with its IMA system, Honda created an even more fuel-efficient vehicle.

If you were to pull the engines out of both a standard Civic and a Honda Civic Hybrid and place them next to each other, you would likely notice the similarities end with the flywheel assemblies. Instead of a flywheel, the hybrid Civic has an electric motor mounted on the end of the crankshaft. It's this motor that makes up the electric component of the hybrid system. The motor is constructed of high-density coil windings and high-performance magnets. The electric motor doubles as a starter motor and is used to provided propulsion and assist under several driving conditions.

The trick to how the IMA and similar hybrid systems work is the relationship between the electric motor and the engine. Honda's IMA system substitutes the engine's internal combustion power for electric power under certain circumstances. We'll let you know what those specific driving conditions are on an upcoming page. But for now, it's good to know that the energy for the electric motor comes from a nickel-metal hydride (NiMH) battery. The battery is charged under deceleration, particularly braking. The Civic Hybrid has a regenerative braking system that works to transform the electric motor into an electric generator under braking. This energy is then stored in the battery for future use.

Up next, we'll get to the nuts and bolts of the Civic's hybrid engine.


Honda Civic Hybrid Specs

So, you may be wondering what exactly makes a hybrid car a hybrid, anyway? What's the difference between a hybrid and a typical car? The short answer is, not a whole lot. But there is a lot of sophisticated electrical technology in a hybrid that's somewhat transparent to the driver and passengers in a hybrid. In a nutshell, hybrid power, as in the case of the Honda Civic, Toyota Prius and other popular hybrid models on the market, is part internal combustion and part electric power. The two systems work in unison to move the vehicle. For an in depth understanding of hybrid engines and cars, read the article, How Hybrid Cars Work.

The 2009 Civic hybrid engine is Honda's fourth-generation gas-electric power plant. Similar to the engines found in the rest of Honda's lineup, the Civic Hybrid is equipped with an inline 4-cylinder engine featuring a three-stage version of the company's VTEC (variable valve timing and lift electronic control) system. It's called the i-VTEC (intelligent-VTEC) system. The three-stage i-VTEC system uses three separate stages of valve control to optimize efficiency at low-rpm, high-rpm and at idle. The three stages utilize five rocker arm assemblies dependent on engine rpm and driving conditions. Computers analyze all the variables and adjust the camshaft profiles to maximize power and efficiency. To aid in the engine's overall efficiency, the computer brain of the system shuts down and seals the combustion chambers in each cylinder when the engine is at idle, under deceleration. This measure adds an additional 10 percent fuel efficiency over the first-generation Civic Hybrid engine.

Keeping along the lines of efficiency, Honda implemented creative friction-reducing construction methods when building the internals of the engine. For instance, the pistons are crafted from die-cast aluminum that doesn't expand much. The result is less expansion and reduced friction under extreme temperatures. The cylinder walls have been plateau-honed, and ion-plated piston rings make for silky smooth operation under power.

A continuously variable transmission (CVT) feeds the engine's power to the front wheels. According to the manufacturer, the 1.3-liter engine provides the Civic Hybrid with 110 horsepower and 123 pound-feet (167 newton-meters) of torque. And, as you might have guessed, the fuel economy numbers are pretty good, too. The Honda Civic Hybrid is said to achieve 40 miles per gallon (17 kilometers per liter) in the city and 45 miles per gallon (19.1 kilometers per liter) on the highway. For comparison, the standard Honda Civic gets 26 miles per gallon (11.1 kilometers per liter) in the city and 34 miles per gallon (14.5 kilometers per liter) on the highway.

So, maybe you've had enough of all of these numbers and you just want to know what it's like to actually drive a car like the civic hybrid? Well, read the next page to find out.

Driving the Honda Civic Hybrid

A Honda Civic Hybrid car and its displayed engine, left, are seen at an event in New Delhi, India, on June 18, 2008.
A Honda Civic Hybrid car and its displayed engine, left, are seen at an event in New Delhi, India, on June 18, 2008.
AP Photo/Gurinder Osan

To experience a somewhat low-tech example of the hybrid driving experience, you don't have to go any farther than your local golf course. Have you ever driven a gas-powered golf cart? Well, if you've never driven a hybrid car, the golf cart example may be the best way to describe how it feels -- sort of.

If you're familiar with gas-powered golf cart operation, then you know that the engine in the cart doesn't continuously run while you're on the fairway hitting your approach shot to the green. Instead, the engine comes on as soon as you press the gas pedal. Hybrid vehicles, like the Honda Civic Hybrid, work in a similar way. Of course, the Civic Hybrid is far more advanced -- and then there's also that bit about the electric motor, too. And that's why the Integrated Motor Assist (IMA) system that you learned about earlier is so important to the Civic Hybrid.

Here's how the Honda Civic Hybrid's i-VTEC engine and electric motor work together in various driving conditions:

  • At a stop: The engine is off and no fuel is being consumed.
  • Initial acceleration: The electric motor powers the Civic Hybrid away from a stop, and the engine starts and operates at the low-rpm valve timing stage.
  • Hard acceleration: The engine operates at the high-rpm valve timing stage along with assistance from the electric motor.
  • Driving at low speeds: The combustion chamber of each cylinder is sealed, and the engine stops running. The Civic is powered by the electric motor only.
  • Deceleration: The combustion chamber of each cylinder is sealed, and the engine stops running. The electric motor switches modes from providing power to storing energy for the battery.

Pretty cool stuff, right? And all of this works seamlessly so that the driver doesn't have to do anything other than drive the car as he or she normally would.

If you'd like more information about the Honda Civic Hybrid and other hybrid vehicle technology, follow the links on the next page.

Related HowStuffWorks Articles


  • Healey, James R. "Undercover hybrid's a winner." USA Today. Jan. 9, 2009. (March 21, 2009)
  • Honda. "2009 Honda Civic Hybrid." (March 17, 2009)
  • Honda. "Honda Insight -- Integrated Motor Assist." Sept. 15, 2000. (March 21, 2009)
  • "Integrated Motor Assist System." (March 21, 2009)
  • Levenstein, Steve. "Made in the USA Honda Accord Celebrates 25th Anniversary." (March 21, 2009)
  • Reynolds, Kim. "Road Test: 2006 Honda Civic Hybrid vs. 2006 Toyota Prius & 2005 Honda Accord Hybrid vs. 2007 Toyota Camry Hybrid." Motor Trend. (March 29, 2009)
  • Schroeder, Don. Car & Driver. "How We Won the Insight Fuel-Economy Challenge. Without Cheating. Much." Jan. 2000. (March 21, 2009)
  • "New Honda Hybrid Engine System." July 5, 2005. (March 19, 2009)