Up to this point, we’ve spent a lot of time going over the losses in gas and diesel powered vehicles. Now, it’s time to talk about the solutions the automakers have come up with to reduce these losses, and how to get even more mileage out of these vehicles.
Hybrid vehicles are gas vehicles with some electric vehicle components to help get the most out of the gas motor. They achieve higher efficiency by reducing losses suffered by regular gas vehicles.
The gas engine still suffers the loss of energy to heat, but by being able to call on electric for backup, the use of the gas motor can be reduced. Standby (idle) losses are reduced to near zero, because the gas motor turns completely off when stopped at lights, etc. Also, electric motors can kick in during acceleration, allowing the gas motor to use less gas while taking off.
Hybrids and EVs brake differently from normal gas cars. They use regenerative braking to collect some of the lost energy when braking and put it back in the battery. When slowing down, the car pushes the motor instead of the motor pushing the car, and it acts as a generator.
Regenerative braking is certainly better than mechanical brakes, but there are still losses and it only recovers a fraction of the kinetic energy. You’re better off to drive in such a way as to avoid braking of any kind, and then try to use regenerative braking more than regular braking when you can’t avoid it. See the upcoming section “Your car is a battery” for more details on the best mix of coasting, regen braking, and mechanical braking.
When using the brake pedal, the EV or hybrid does a mixture of normal braking and regeneration. In an empty parking lot or a road with no traffic, practice using regeneration by itself to see how it feels and how well it stops the car.
There might be a “B” or “L” position on the shifter you can use, or if your car uses “one pedal driving”, you can just release the gas pedal to apply the regenerative brake. Some models regenerative brake with a light press of the brake pedal, and put on the mechanical brakes with harder presses. Newer Chevrolet Volts and the Bolt EV have a “paddle” on the steering wheel to activate regenerative braking on its own.
Many models have settings you can change to make regenerative braking more aggressive (B mode and/or Eco mode). They don’t turn these on by default because it feels different to drivers who are used to regular brakes. Turn regenerative braking to its strongest setting for best results, but don’t overuse it. See your owner’s manual for instructions.
If your car starts regen when you release the gas pedal, you’ll need to learn where to put the pedal for effective coasting. Releasing the pedal enough to stop accelerating, but not too much to where it regen brakes is the trick. When you find the right “happy medium”, you’ll be able to coast farther and then release the pedal to start braking at the right time for maximum efficiency.
Types of Hybrids
Parallel hybrids are more similar to regular gas/diesel vehicles. The difference is that the transmission is set up to accept power directly from both a gas engine and one or more electric motor. Depending on what you’re trying to do, the car can use the gas motor alone, the electric motor(s) alone, or go all in putting power from all sources for maximum acceleration.
As you’ve probably guessed, running all motors full-tilt at the same time tends to burn a lot of gas. This is the first thing you need to avoid to get the most out of a parallel hybrid. In fact, generally you want to avoid running the gas motor as much as the car will let you.
Most hybrid cars have “modes” you can choose from. To save gas, stay away from “power mode”, “performance mode” or “sport mode”. Use the “eco mode” or similarly named modes as much as possible.
For maximum savings, some parallel hybrids have an “EV” mode, where the gas motor avoids coming on. This mode might only work below certain speeds and only for a limited range. Read your owner’s manual to learn the limits of EV mode for your model.
Unlike a parallel hybrid, a series hybrid’s gas or diesel engine does not directly give its power to the wheels. Many diesel trains have run this way for a long time, with great efficiency. This is because the gas or diesel motor doesn’t have to vary the amount of power it puts out. The engine can be optimized for putting out a certain amount of power at a certain engine speed and do a great job of that.
When the driver needs a surge of power beyond what the gas engine can create, the batteries are used to give that extra surge of power, and the gas engine can catch up on charging when the car isn’t going so fast later.
The amount of time spent with the gas/diesel burning fuel depends on the charging needs of the batteries. You can run the batteries down and have that gas/diesel burning almost constantly, or take it easy and let it shut off more. You can also use regenerative braking as described above to reduce need for gas/diesel.
Blurring The Lines
Some vehicles blur the line between a pure hybrid and a pure EV. The difference gets really blurry in terms of marketing, reviews and expert discussion, so you’ll need to learn about a vehicle to see what type it is, and whether it will work for you.
Plug-in Hybrids (PHEV)
A plugin hybrid is like a normal hybrid, but doesn’t get all of its electricity from the gas/diesel engine. You can charge the battery at home during the night so it’s “topped off” when you leave. You can also plug in the car at most level-2 EV charging locations, possibly including your work.
The advantage to a PHEV is that electricity is cheaper than gas, and by “topping off” the battery, you can use the gas motor less or possibly not at all, depending on the model. Some PHEVs have larger batteries than the average hybrid for greater all-electric range, and some do not.
Range Extender EVs
Now we’re getting into the blurriest part of the hybrid vs EV discussion. Technically a range extender EV is still a hybrid because it uses gas or diesel part-time, but depending on the owner’s habits, gas or diesel might never be used at all, or very rarely.
Electric Vehicle (EV) batteries are expensive to make, heavy, and don’t get used for more than a few miles on most days. Nearly all commuters travel less than 50 miles, with the average commuter going 15 miles each way in a day. By having an EV with a 50-100 mile range, it more than covers daily driving needs. But selling a low range EV is tough, because most people don’t want to have to switch cars or rent a car for road trips. Plus, some people only can afford one car.
Theadvantage to the range extender EV is that it’s a pure EV for most driving, but has a gas or diesel generator on standby to charge the battery if it gets low. At that point, it becomes a series hybrid. This helps keep the cost of the car down while providing the EV experience.
To further complicate things, range extender generators may become available as accessories for vehicles sold as pure EVs. The idea is that an EV driver can stop at a rental place and pick up a generator trailer for long trips. But, as battery prices fall with mass production, this idea might go away along with range extenders built into vehicles.
Electric Vehicles (EVs)
Much of what has been discussed so far about hybrids also applies to electrics. The biggest difference is that there’s usually no gas/diesel engine involved. There’s just a charger, battery, controller, and motor powering the wheels. As you can see from the picture above, they’re extremely efficient.
- Minor charging and drive system losses
- No idle/standby losses (except accessories and climate control)
- Simple drivetrains minimize further losses
- Regenerative braking pushes efficiency up to over 90% in city driving
Electric vehicles also have great performance potential. Maximum torque is available from 0 RPM, making performance EVs such as Teslas even better than most gas cars for acceleration.
Disadvantages (with present battery technology, mid 2017):
- Best real-world ranges are around 300 miles for average drivers in high-end cars. Most are far less, around 100 miles.
- Weight higher for longer range cars
- Sustained hard driving often causes battery overheating (but in normal non-racing use, and as an eco driver, this shouldn’t be a problem for you)
How to get the most efficiency/range out of an EV
Using the eco driving techniques from this course can’t help you get more miles per gallon because there are no gallons. What you’re aiming for as an EV eco driver is maximum range from your battery and less charging at home or charging stations. This is measured in units like miles/kWh or Wh/mile.
The first thing to keep in mind is that while efficiency before the wheels is far greater, efficiency after the wheels is subject to the same losses as a gas/diesel car: aerodynamic losses, rolling resistance, and braking.
If you’re an EV driver and skipped the last few sections (you shouldn’t have), at the very least go back to the “Losses After The Wheels” section. Everything that you read there applies to EVs. EVs almost always come from the factory with great aerodynamics, low resistance tires, and regenerative brakes, but they’re not perfect and still benefit from most of the methods taught in this course for gas/diesel vehicles.
Also, review the sections above about hybrids, especially regenerative braking. That applies double for EVs. Be sure to check out your user manual and learn all you can about how regenerative braking works in your particular model.
- It might be controlled by the gas pedal (one-pedal driving, Tesla)
- It might be controlled by the shifter or a special switch (ex. Toyota Rav4 EV uses Prius shifter)
- It might be controlled by light brake presses
- You might be able to change settings for more aggressive regenerative braking. Do this, and don’t freak out when it feels different. Get used to it, and reap the benefits.
Finally, environmental controls are a big deal for EVs. Both heat and A/C use your battery and the heater is worse for rangethan the A/C. Minimize your use of both for maximum range (but keep windows rolled up on the highway!). When it’s cold out, use the heated seats to stay warm in the beginning and slowly warm up the cabin rather than turning the heat on full blast.
If you’re leaving from place with the car plugged in, set the EV’s timer to complete charging 15-20 minutes before expected departure so the batteries will still be warmed up. Then start the heating or A/C 10 minutes before departure either on a timer, or on a mobile app. That way, your warmup or cabin cooling happens while it’s still plugged in, and doesn’t eat up battery range getting it comfortable enough for you.
It’s still a car!
Electric vehicles are designed to be very efficient, but the following lessons in the next section will definitely apply to them.
Don’t Count Out Gas and Diesel Just Yet
While electric vehicles, and to a lesser extent hybrids, are clearly a superior vehicle for efficiency, don’t assume that gas cars are going to completely go away in the future. Don’t assume that because you have a gasser that you need to get rid of it.
One man took his stock 1992 Honda Civic and did aerodynamic modifications totaling $400. This got him to 95 MPG on the highway, a figure rivaling the “MPGe” ratings of many electric cars. Do-it-yourselfers and manufacturers both are going to be making great strides with gas in the future, and will continue to compete for efficiency.
One promising technology is HCCI, or Homogeneous Charge Compression Ignition. Gas engines will outperform today’s diesel engines with better emissions and better efficiency. Other technology, like variable displacement, electric turbos, heat capture, and many others will step up to the plate and give electric a run for its money, possibly at lower costs.
If you want an electric, don’t let me talk you out of it, but if you are a traditionalist and want gas, there’s probably a future there, too. And if you are on a budget, hyper-efficient gas cars are probably going to be there for you far into the future.