How Does A Hybrid Vehicle Work?

If you are looking to new car, you may wonder about the differences between a conventional vehicle and hybrid vehicles. Most hybrid cars on the road today have a conventional counterpart. The Toyota Prius is one exception. Toyota also plans to make a Lexus HS250h, which will have no conventional equivalent. For the most part, however, you will be able to compare a hybrid model with its conventional cousin. The main differences between the 2 types of vehicles are how they get their power. Hybrids use both gas and electric to power/push the vehicle where as conventional automobiles use gasoline only.

Hybrid Vehicle Types

The fuel efficiency of the hybrid vehicles depends upon the hybrid design. Two major hybrid designs have emerged, and are referred to as "parallel" and "series." A parallel hybrid design has two independent power plants – an electrical motor and an internal combustion engine. Both of these power sources can act on the transmission at the same time. These power plants combine to drive the transmission, and ultimately the vehicle's wheels. Each of these power plants can also drive the transmission independently to offer all-electric or all ICE drive. Normally, an all-electric mode would handle low-speed situations, like idles and cold-starts, or a "maintenance" situation, like cruising at highway speed.

In contrast, a series hybrid design uses the internal combustion engine to power a generator. The generator then powers the vehicle's transmission, or charges the batteries in the car. The gasoline engine does not directly drive the transmission or wheels in a series hybrid design, and the transmission may have only a single gear. In certain designs, each wheel has its own electric drive motor, and some hybrid designs may eliminate the transmission altogether.
Another component of fuel efficiency is the size of the internal combustion engine in a hybrid vehicle. Manufacturers can afford to put much smaller engines in their hybrid vehicle designs because the goal of the engine in a hybrid isn't to allow the vehicle to reach a certain top speed, but rather to meet the average power needs of the vehicle. Many passenger hybrid vehicles use engines with displacements in the 1L-2L range. These engines would be too small to provide adequate power to a conventional vehicle, but the hybrid system acts like a booster to provide the power the vehicle needs for acceleration, climbing and in some cases, towing.

How Hybrid Vehicle Work Cont.

For certain hybrid vehicle designs, (primarily trucks) the internal combustion engine is much larger – in the 4L-5L range or better. In these vehicles, the hybrid system is used to boost fuel economy. The addition of the hybrid system reduces some of the vehicle's towing capacity in exchange for better average fuel economy.

Several pickup trucks and SUVs use hybrid systems to provide a needed power boost for towing and climbing, and to maximize fuel economy at highway speeds. In this case, the hybrid system helps maintains the vehicle's cruising speed, allowing the engine to switch from an 8-cylinder operation to a more efficient 4-cylinder one while the vehicle is in motion. These vehicles typically have very similar or equal city and highway mileage ratings.

For drivers of hybrid vehicles, in most cases, it is difficult to tell when the hybrid drive system is active. Special gauges have been developed to help drivers learn how to maximize their fuel economy in a hybrid vehicle. These gauges may also keep track of the vehicle's emissions. Hybrid drive systems pose other challenges, too. For example, manufacturers' recommendations regarding oil changes and maintenance intervals may be difficult to follow, since the internal combustion engine usage is no longer directly related to odometer mileage.