You’ve probably heard more than a dozen times that EVs (electric vehicles) are more efficient than conventional internal combustion cars. But what does that really mean? And are they slightly more efficient or significantly more?
I remember a similar debate almost 2 decades ago: the efficiency comparison between gasoline and diesel. Diesel engines were getting more efficient, providing more performance, and better economy. And doing it with smaller displacements (engine size) than before.
Here in Europe diesel cars were a big deal for over a decade. In some European countries, diesel had a market share of over 70% for some time. Yes, diesel is still around but far from being in the spotlight like before.
But enough about diesel and back to our topic for the day.
When someone says that…
An EV is more efficient than a gasoline vehicle…
Think of efficiency as the relation between input and output.
You want to use the less possible gasoline to get the most movement, distance, and power possible.
Manufacturers have been improving that ratio considerably for decades. But if you compare it to EVs… the game is over before it even starts.
Before we go further into each of the topics for each of these types of vehicles.
Gasoline car efficiency
When you burn a liter of gasoline only a part of it is useful for moving the wheels. Actually less than 30%. Wait… what?!
Yes, you got that right. A great deal of that liter will be lost along the way. Let’s see how.
First and foremost: around 70% of the losses are in the engine department. Almost 60% are just down to thermal matters such as radiator and exhaust.
Have you ever stopped your car after driving for a while on the highway and noticed a lot of heat near the engine bay or the exhaust tailpipes?
Let me tell you that if you would open the hood you would feel stronger heat coming from the engine. Maybe you would even feel the warm hood.
Then there are much smaller losses like pumping, combustion, and friction which make it add up to around 70%.
These are losses like those of the water, fuel, and oil pumps. You can’t cut back on having your engine cooled up to temperature, being fed the necessary fuel, and being constantly lubricated, right?
In this category, we also include ignition systems and engine control systems, among others. These are responsible for losses between 4% and 6%.
After losing considerably on the engine department, it’s time to move on to the drivetrain, as the power transfers from the former to the wheels.
Losses here equate to around 3% to 5%.
Auxiliary Electrical Losses
A modern car is far from just an engine and transmission doing its work to move it.
You have a long list of devices working and they’ll cut you back up to 2%. Some of them are for safety or drivability. Then you have some meant to provide better comfort and even entertainment.
Here you can group lighting equipment (like the headlights) but also climate control and steering wheel and seat heaters. Yes, your stereo and navigation systems will also take their share.
How much efficiency or power reaches the wheels of a gasoline vehicle?
Like you probably figured out already, not much. Around 16-25%.
If you use 100 liters of gasoline, only 16-25 actually get to move the wheels.
And you’re about to lose even more of it.
This efficiency will dissipate even further:
- Wind resistance (8-12%)
- Rolling resistance (4%-7%)
- Braking (4%-7%)
What do these have to do with losses?
Well, the faster you want to go, the higher the wind resistance is. If you’ve ever stopped accelerating at high speeds you noticed that the car lost speed quickly.
Rolling resistance is also a thing, tires are the only contact with the road.
Braking also requires power.
We come down to figures of around 75% to 84%.
Now let’s go to the EV arena for something completely different, this is gonna be shocking.
Electric vehicle efficiency
Just to remember… a gasoline car is about 16%-25% efficient, meaning… losses sum up to 75%-84%.
Get ready for some major efficiency…
Well, maybe not yet…
Yes, EVs start losing even before they move. Not the start you were hoping for, right?
It’s true, they have losses of around 10% in the charging process.
It gets worse though…
Electric Drive System losses
If 10% seemed a bit, now we are going for around 18% losses.
The electric motors might be very efficient but there are still losses when turning the energy from the battery into power and movement at the wheels.
Auxiliary Electrical Losses
Like in any regular vehicle, you will still have losses of some common equipment.
Among them are headlights, climate control, heated seats, and heated steering wheels.
Unlike gasoline cars (0-2%), here they go up, 0-4%.
Ok… I know what you’re thinking. I promised EVs would be a lot more efficient and it’s not looking bad but it’s also not looking stellar…
Well, get ready, because now we’re in for a wrap-up.
Do you know what happens in an EV when you stop in traffic?
The electric motor uses around 0% of energy.
At the moment we’re getting 65%-69% efficiency.
And now we’re going to go even further…
Regenerative braking will be responsible for a further loss of…. no, actually, it won’t!
In fact, it will be recovering energy for you.
Imagine you’re driving at 120 km/h on a highway and you’re about to slow down to stop at a service station. We all need to use the toilet and recharge our inner batteries, right?
On a gasoline car, you could let go of the throttle but braking will also be at play.
On an electric vehicle? Instead of the car just coasting (rolling without the engine or brake system slowing it down), the motor will act as a generator.
That means that you’re going to stop a lot sooner than if you were coasting. But that’s not all.
Your car will recover some energy and feed it back to the battery.
It’s estimated that regenerative braking can get you back 22% of efficiency.
How much efficiency or power reaches the wheels of an electric vehicle (EV)?
Not the 16-25% you would get on a gasoline car.
You’ll actually get 87%-91% of efficiency.
If you use 100 kWh, you actually get 87-91 kWh to move the wheels.
An EVs efficiency is still dissipated further:
- Wind resistance (39%)
- Rolling resistance (25%)
- Braking (25%)
Why do these figures get more significant than those of the gasoline car?
That’s because the EV is much more efficient. The gasoline car, because it’s so less efficient, uses a lot more energy (fuel). And that’s why these resistances end up by being smaller (in relative terms).
Conclusion on Car Efficiency – Gasoline vs Electric vehicle
For years we’ve seen the gasoline car as the standard fuel for cars. And for good reason, they’ve come a long way, decade after decade.
Gasoline cars still have their place. The internal combustion engine is not dead.
I love electric cars… and I love gasoline cars.
But the tendency is that electric cars will keep on gaining market share and become dominant. And their efficiency and local zero-emissions play essential roles.