Series (Science): Green Machines

Green Machines, Part 4: Hybrid Electric Vehicles (HEVs)

Welcome to the latest installation of a 5-part series about environmentally-friendly cars, entitled Green Machines. To read the previous installation, CLICK THIS LINK. For the next post in this series, CLICK THIS LINK. To start at the beginning, CLICK THIS LINK. Thanks for reading!

Hybrid Electric Vehicles (HEVs)

What happens when an Electric Vehicle (EV) is left alone with a full gas-powered vehicle? A few months down the line you get a Hybrid Electric Vehicle (HEV). Or so I was told by an auto expert who got tired of all my questions. He also called me a jackass.

HEVs are the mules of car ownership.

And that leaves me comparing HEVs with mules. A mule is a cross between a horse and a jackass. In the same vein, full gas-powered cars tend to have a lot of horsepower. But those who drive EVs tend to be smartasses, always bragging about how they’re saving the environment. Combine the two and you get an HEV, the mule of car ownership these days.

HEVs are mules because they can do more work than EVs or full gas cars. They get more range than EVs, or even full gas cars, gallon for gallon. And they get better gas mileage, and tend to be more reliable than full gas cars.

They’re a hybrid, but don’t confuse them with a so-called green vehicle called a “Mild-Hybrid” (or “Micro-Hybrid”). Mild Hybrids are full gas-powered vehicles with a start/stop system. They shut the engine off when you stop, then restart the engine when you take off. This improves gas mileage around a city, but only by a smidgen of maybe 1.5 mpg. The slight savings in fuel economy is often not worth the extra cost for a Mild Hybrid. Also, all that starting and stopping is wearing on an engine, as well as on the starter.

Chrysler sells a lot of Mild Hybrids, so beware, you Chrysler lovers.

HEVs have both an electric motor and a gas-powered, internal combustion engine. The gas engine tends to be smaller than what you’ll find in a full gas-powered car. When you’re driving an HEV around in the city, the electric motor tends to do most of the work. But when you get out on the highway, the gas engine kicks in and helps the electric motor. The combined energy they both put out brings the HEV’s horsepower up to par with that of a full gas-powered car.

HEVs tend to be more complex than full gas cars. Except in the case of the Series Hybrid design. In this design, the gas engine only recharges the batteries, and nothing more. The electric motor does all the work, at all speeds. This eliminates the need for a transmission, making for a simpler drivetrain. However, it tends to be less efficient at highway speeds than a full gas car, because of the indirect connection of the engine to the wheels, through the battery.

Most HEVs these days are of the Parallel or Series-Parallel design. These designs are more fuel efficient than Series Hybrids.

A Parallel Hybrid is more complex than both a Series Hybrid and a full gas-powered car. With this design, both the gas engine and the electric motor power the wheels. However, the gas engine requires a transmission, and this complicates the mechanics of the operation. Also, the gas engine does not recharge the battery.

Many HEVs these days are termed Series-Parallel (or Power-split). These are the most complex of the hybrids. They combine the advantages of both Series Hybrid and Parallel Hybrid designs. The gas engine can power the wheels through a transmission, and it can also recharge the battery. Meanwhile, the battery powers an electric motor that connects to the transmission through a complex and magical “power-split” design. To handle this complexity, computers figure out the best mode of energy use in any given driving situation.

HEVs tend to get 20% to 35% better gas mileage than full gas cars. However, compact HEVs tend to sacrifice horsepower for great gas mileage. For instance, the 2022 Toyota Prius only has 121 wimpy horses under the hood. But it sports a whopping 56 mpg. SUVs, on the other hand, tend to have respectable horsepower, but get less gas mileage. For instance, the Hyundai Santa Fe Hybrid has 226 horses, but gets only 32 mpg.

Yes, even with the design of HEVs, an aggravating compromise has to be made between gas mileage and horsepower.

As far as range is concerned, you’d think with their superior gas mileage, an HEV would have more range than a full gas-powered vehicle. But alas, car manufacturers often design their HEVs with smaller gas tanks, to make them lighter in weight and more energy efficient. This keeps their range only slightly longer than their full gas engine counterparts, as a general rule.

HEVs tend to require the same amount of regular maintenance as full gas cars, such as recommended oil change intervals. But in spite of that, they tend to have fewer mechanical problems. That’s because their gas engines run for fewer miles, at less RPMs, and at more stable speeds. Also, they have continuously variable transmissions that never disengage and reengage the engine. Thus, HEVs experience less wear-and-tear, and this makes them more mechanically reliable, in spite of their greater complexity.

The norm in the auto industry is to warranty HEV batteries for at least eight years or 100,000 miles. But these days, batteries are often expected to last 10 to 20 years. It can be damned expensive to replace them, but if you buy your HEV brand new, you won’t have to worry about this for a long time.

Some HEVs are also PHEVs. That stands for Plug-In Hybrid Electric Vehicle. But most HEVs can’t be recharged by plugging them into a wall. Rather, they are only recharged through regenerative braking and the gas engine.

But you can plug a PHEV into a regular wall outlet in your garage, and charge the battery. You can generally get about 30 to 40 miles of city driving range from a fully-charged PHEV battery. So if you don’t drive much, a PHEV allows you to rely on electricity alone, without ever having to fuel up at a gas station.

I like the idea of a PHEV. Most of the year, I don’t drive much. But occasionally I go on long road trips. A PHEV would allow me to have the equivalent to an EV most of the time, while having an HEV when I want to drive out of town. They’re more expensive than an HEV, but I like the idea of not having to rely on gas stations for my short-range driving needs. This could come in handy during a gas shortage.

And so I’ve decided. When I get ready to buy a green machine, I will be buying a PHEV. I’ve researched some of the models currently available, and will share the results in my next post.

Some of my sources:
Wikipedia: Hybrid Vehicle Drivetrain


13 replies »

    • Thanks. I haven’t bought it yet. Probably won’t bite that bullet until next year, but it’s encouraging to know how happy you are with your PHEV. There’s one final post on this subject, coming up in a few days.

      Liked by 2 people

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