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How Hybrid Cars Work

hybrid car
Teddy Leung /

What is a hybrid car?

A hybrid car is one that uses more than one type of drivetrain to make movement. Most of the time, this means that the car takes gasoline to power an internal combustion engine and has batteries to power an electric motor. The aim of hybrids is to provide the owner with superior fuel economy while still allowing them the convenience of filling up their cars at standard gas stations. There are perks and drawbacks to every hybrid car, and with their popularity still rising ever since their introduction in the North America in 1999, they are poised to remain popular for some years to come.

How does a hybrid car work?

There are two major types of hybrid that currently dominate the market:

  • Series Hybrid: Hybrids that have electric motors sending power to the wheels. Called a Series Hybrid, this type uses the gasoline-powered engine as a generator and otherwise functions like a fully electric car. The power going to the wheels is all electric in origin, with the power for the electric motors coming from the batteries that are charged by the gasoline engine. Cars with this arrangement don’t need a transmission and can usually be plugged in as well so that even less gasoline is used for the first miles of a journey. They also tend to have larger batteries than Parallel Hybrids. The Chevrolet Volt and the now discontinued Fisker Karma use this type of system.

  • Parallel Hybrids: Hybrids that have both electric and gasoline-powered motors powering the wheels. Called Parallel Hybrids, this type sends power to the wheels and generates electricity with the gasoline engine. The arrangement resembles that of a standard combustible-fuel powered car, the only difference being the electric motor assisting the engine. The electric motor is placed somewhere along the drivetrain, usually between the engine and the driveshaft. This is the most common type of hybrid car available today. Cars that are produced as a hybrid version of an already popular car usually adopt this arrangement. The Honda Civic and Chevrolet Malibu hybrids are good examples of this type.

  • Series-Parallel Hybrids: Hybrids that are able to switch between a gasoline engine and an electric motor or use both at the same time. Called Series-Parallel Hybrids, this type can power the wheels with either the electronically assisted gasoline engine or the electric motor alone. Allowing each motor to play to its strengths, series-parallel hybrids make the most out of whatever fuel is used by accelerating from low speeds with only the electric motor and using the gasoline engine to travel along at highway speed. This layout is increasing in popularity and is used most famously in the Toyota Prius. Mercedes and BMW are also producing hybrid vehicles of this type.

How do hybrids save fuel?

Hybrids that can be plugged in are appropriately called Plug-in Hybrids and save fuel by filling the batteries up with power from an outlet. Plug-in hybrids are the closest someone can get to having a fully electric vehicle while still being able to utilize gas stations. The batteries normally would be charged by the engine burning gasoline. Because there is so much emphasis on fuel efficiency in the design of hybrid cars, the technology that has been developed to help vehicles use less fuel is impressive.

When braking, the electric motor switches off and is rotated by the momentum of the vehicle while still coming to a stop. This is called Regenerative Braking, and it is unique to vehicles with electric motors in the drivetrain. Some hybrids do such a good job at this that they barely need the gasoline engine to generate any electricity to charge the batteries.

Hybrids also have the ability to start a gasoline engine with no starter motor. Instead, the engine starts when it is spun by the electric motor. Because of this, hybrids are able to seamlessly shut off the engine when the vehicle is stopped and restart it again when the brake is released. Called Automatic Stop-Start, this technology eliminates fuel waste from idling. While some gasoline-only vehicles use this feature, it is present on nearly every hybrid.

What hybrids work for what applications?

  • Commuting or traveling short distances: A hybrid with a large battery and the ability to run on fully electric power would be most beneficial to this application. Because series or series-parallel hybrids generally have enough battery to go short distances on only electric power, they would conserve the most fuel compared to a gasoline vehicle. Plug-in functionality is a huge plus as well for this application.

  • Long commutes (50 miles and up) or long-distance travel: A series hybrid or series-parallel hybrid would be most useful for this application. Because the gasoline engine will be running most of the time and the car will probably be moving at highway speed, a hybrid with a large electric motor will save the most fuel compared to a gasoline vehicle. Many parallel hybrids have a small electric motor to save fuel at low speeds that is not nearly as useful at highway speed.

  • Performance: A series-parallel hybrid would definitely be the only choice for a performance vehicle. A series hybrid cannot utilize the gasoline engine for wasteful open-throttle driving to race speed. A parallel hybrid isn’t likely to have an electric motor large enough to perform at high speeds.

Hybrid vehicles today

Modern hybrid vehicles are becoming more and more like electric vehicles with every passing year. Battery technology has greatly improved at the same time, and the cost of batteries has decreased. While there are viable electric vehicles on the market made by Tesla, Nissan, Mercedes-Benz, and others, the infrastructure to charge electric cars over long distances isn’t there yet. Hybrids are a placeholder for this, and will only be viable as long as gas stations are around.

That said, gas stations will probably be around for a while. So a hybrid may be a smart investment when you consider the saved fuel and the high resale value. On the other hand, hybrid vehicles are heavier than their single-drivetrain alternatives. They also use more parts, so there is more that can break. Much of the newer technology hasn’t been around for more than a decade, so long-term durability is mostly speculative. Still, using fuel more efficiently is a respectable goal and automakers are working hard to make vehicles run cleaner and greener every day. If a hybrid seems like the right choice, then it is, at the very least, worth considering.

Maintenance and other concerns

A very interesting aspect of hybrids today is the maintenance once these vehicles start hitting high miles. Each year new advances and technologies pop up and manufacturers scramble to get them into their cars to sell to consumers. Some will be very reliable while others may gain a reputation for being problematic.

If you own a hybrid, treat it like a normal car and have it inspected when there are error messages or the Check Engine Light comes on. Address any issues with the suspension, wheels, or steering just like you would with any other car. Just know that there will be certain problems that may be unique to your vehicle, and that a qualified mechanic will be able to assist you if you encounter any problems.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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