"A car that feels incredibly fast even when not going that fast."
On the other hand,
"A car that doesn't feel very fast, even though it's actually quite fast."
also exists.
For example, a low and compact sports car can feel fast even at 60 km/h.
Conversely, in large cars with high quietness and stable bodies, the sense of speed may feel diminished even when driving on expressways.
Why do such differences arise?
The "speed" a person perceives is not solely determined by the speedometer reading.
Acceleration.
Change in acceleration.
Throttle response.
Vision.
Sound.
Vibration.
Vehicle height and seating position.
Vehicle movement.
The brain synthesizes a lot of information, such as these, to make its judgment.
This time, we will explain why the actual speed and the sensation of "feeling fast" do not always align, from the perspective of human perception.
"Actually fast" and "feeling fast" are different
First, it's necessary to consider these two things separately.
Actual speed can be measured by numerical values such as:
How many kilometers per hour it's traveling.
How many seconds it takes to go from 0-100 km/h.
How many seconds it takes to cover a certain distance.
On the other hand,
The sensation of "feeling fast"
is human perception.
Even at the same 60 km/h,
The car model.
The road.
Sound.
Vibration.
Visibility.
How it accelerates.
The feeling changes depending on these factors.
In fact, a previous article, "Why two cars with the same 100 horsepower can feel different in speed," also explains that the speed a person perceives and the measured speed do not always match due to factors like engine sound, ride height, vibration, and throttle response.
This time, we will delve deeper into "what clues do people use to perceive speed?"
Reason 1: Higher acceleration makes it feel faster
There's a significant difference in how it feels when a car is moving at a constant speed versus when it's accelerating.
For example, accelerating from 30 km/h to 70 km/h quickly can sometimes feel "faster" than driving at a constant speed of 100 km/h on a highway.
This is because the human body perceives not just the speed itself, but also the acceleration when the speed changes.
Strong acceleration pushes the body back into the seat.
That physical sensation is transmitted to the brain as information that "the car is rapidly increasing in speed."
In other words, when considering perceived speed, acceleration is just as important as vehicle speed.
Reason 2: Even with the same acceleration, the "initial response" changes the impression.
What's even more interesting is that even with similar acceleration performance, the impression can differ depending on how the power is delivered.
For example, let's say car A has the following characteristics:
You press the accelerator.
Torque increases smoothly.
Acceleration gradually becomes stronger.
On the other hand, car B has the following characteristics:
You press the accelerator.
A large amount of torque is instantly generated.
Your body is abruptly pushed back into the seat.
Even if the final speed and acceleration times are similar, car B might feel "faster."
This is where "jerk" comes into play.
Jerk is a measure of how much acceleration changes over time.
In ride comfort research for automobiles, it has been studied that not only acceleration but also jerk affects how occupants perceive movement and their comfort.
Therefore, for the driver's perceived speed, not only how much it accelerated, but also how the acceleration began, is important.
Cars with sharp throttle response tend to feel faster.
The time it takes from pressing the accelerator to when the driving force is generated also affects the perceived feeling.
A car that moves forward immediately when the accelerator is pressed can feel nimble, even if its maximum output isn't particularly high.
Conversely,
You press the accelerator.
Wait a little.
It shifts gears.
Then it accelerates strongly.
In such a car, even if it's ultimately fast, the initial response feels gentle.
This difference is throttle response.
In other words,
A car with high maximum horsepower
and
A car that feels fast the moment you step on the accelerator
are not necessarily the same.
The sudden torque of a turbo can also emphasize "speed."
In turbo engines, as the engine speed increases and boost pressure intensifies, there can be a characteristic where torque suddenly increases.
For example,
It's gentle at first.
It exceeds a certain RPM.
Torque suddenly increases.
This change is an example.
When acceleration changes abruptly like this, it leaves a strong impression on the driver.
Conversely, in cars that produce large torque very smoothly from low RPMs,
Even though it's actually quite fast, it doesn't feel particularly exciting.
This means that "speed" and "excitement" are not the same thing.
One reason why EVs feel fast
In EVs, thanks to the motor's torque characteristics and control, some cars can achieve significant driving force immediately after accelerator input.
In internal combustion engine vehicles, the process might involve:
Engine speed increasing.
Shifting gears.
Turbocharger boosting.
On the other hand, motors can utilize large torque from low revolutions, depending on the conditions.
Therefore,
The time from accelerator input to acceleration is short.
This tends to create the impression of "fast the moment you press it."
However, even with EVs, the actual response varies depending on the vehicle's control system.
Reason 3: People perceive speed visually.
When driving, vision is extremely important for humans to judge speed.
The road.
White lines.
Guardrails.
Buildings.
Utility poles.
The road surface.
Surrounding vehicles.
All move within the field of vision.
This visual flow is called "optic flow."
Research on speed perception has shown that the visual stimuli and field of view surrounding the road can alter the speed drivers perceive.
This means that even at the same 60 km/h, depending on the scenery, it can feel either fast or slow.
Speed is easily perceived on narrow roads.
For example,
A narrow, single-lane road.
A road with buildings immediately alongside.
A road with close guardrails.
When driving on such roads, even at relatively low speeds, it can feel fast.
This is because surrounding objects pass by you quickly.
Conversely,
A wide highway.
A road with an open view far into the distance.
A road with few surrounding buildings.
On these roads, visual changes feel smaller at the same speed.
In fact, research on drivers' speed perception also shows that speed estimation changes depending on visual conditions such as road width.
Why do low-slung cars feel fast?
When driving a sports car, you might feel like you're going "faster than the actual speed."
One possible reason for this is the seating position.
In low-slung cars,
The driver's eye level is closer to the road surface.
Road markings rush past nearby.
Guardrails and other objects also appear relatively larger.
This condition makes it easier to strongly perceive changes in the scenery moving through the field of vision, which can intensify the sense of speed.
On the other hand,
Large SUVs.
Minivans.
Buses.
In these vehicles, the seating position is higher.
Because the distance to the road surface is greater, the sensation may be different at the same speed.
However, the perceived sensation is influenced by multiple factors such as vehicle size, field of view, and quietness, so it's not solely determined by vehicle height.
Reason 4: Sound is also an important piece of information for judging speed.
It's not only our eyes that perceive speed.
Humans also get information about speed through their ears.
For example,
Engine sound.
Exhaust sound.
Tire noise.
Wind noise.
Gear sound.
A study on in-car sound and speed perception confirmed that drivers tend to underestimate speed when there is little sound.
In other words,
The quieter the car, the less likely one is to perceive the actual speed.
This may be one reason why, when driving a luxury car, people sometimes realize they "were going faster than they thought."
Loud engine noise does not equal actually fast.
Conversely, cars with loud engine and exhaust sounds can evoke a strong sense of speed.
For example,
Engine RPM rapidly increases.
Intake sound gets louder.
Exhaust sound changes.
When such information is received, it's easier to get the impression that the car is "accelerating strongly."
Research on automobile acceleration sounds also shows that engine sound is strongly related to subjective evaluations such as "sportiness."
However,
Loud sound does not equal high acceleration performance.
It is merely one piece of information that creates the sensation.
Quiet high-performance cars can sometimes feel "slow."
High-performance luxury cars are designed to suppress:
Engine noise.
Wind noise.
Tire noise.
Vibration.
Body vertical movement.
As a result,
Even when traveling at very high speeds, occupants receive little stimulation.
Since the information humans use to judge speed is reduced, the phenomenon of "fast but not feeling fast" is more likely to occur.
This is not a sign of low performance; rather, it is a result of high comfort and stability.
Reason 5: Vibration also affects the sense of speed.
In a moving car,
Engine vibration.
Vibration from tires.
Uneven road surfaces.
Suspension movement.
Body vibration.
These are transmitted to the occupants.
These also provide information about the car's movement.
For example, at the same speed,
Stiff suspension.
Low-profile tires.
A car body that easily transmits vibrations.
In such cases, strong road information can lead to a heightened sense of speed and stimulation.
Conversely,
Suspension that effectively absorbs vibrations.
Quiet tires.
A car with high body rigidity and appropriate damping.
In such cases, the sense of speed may be diminished.
However,
A car with a lot of vibration does not equal a fast car.
Here again, it's necessary to distinguish between "performance" and "perceived feeling."
Reason 6: Fast steering response makes the whole car feel fast.
The phrase "feels fast" isn't only used for straight-line acceleration.
Even with a slight turn of the steering wheel,
It immediately changes direction.
The car body follows without delay.
Minimal body roll.
Such a car feels "quick in movement."
This means that the speed a human perceives is related not only to longitudinal acceleration but also to lateral movement.
This is why lightweight cars, cars with short wheelbases, and cars with sharp steering response are often described as "nimble."
"Nimbleness" and "high-speed performance" are different things.
For example, in a small sports car,
Top speed.
Maximum output.
0-100 km/h.
These numerical values may not match those of high-performance cars with large displacements.
Nevertheless,
Good throttle response.
Light body.
Low sightline.
Sensitive steering.
Engine sound is clearly audible.
When these characteristics are combined, it can feel very fast.
Conversely, large high-performance cars,
Overwhelming output.
High-speed stability.
Quietness.
Excellent ride comfort.
Because of these factors, even if they are actually fast, they can feel less exciting.
Therefore,
"A fast car"
and
"A car that feels fast"
are not the same.
Reasons why you might not notice your speed until you check the meter
Perhaps you've had the experience of driving on a highway and thinking, "I didn't realize I was going that fast."
This tends to happen when conditions such as the following overlap:
The road is wide.
The surrounding scenery is distant.
The engine sound is quiet.
There's little wind noise.
There's little vibration.
The car body is stable.
To accurately know the actual speed, it's important not to rely solely on your senses but to check the speedometer.
Human speed perception has errors, and research has reported a tendency to underestimate speed at high speeds.
A car that "feels fast" isn't necessarily a good car.
Considering the joy of driving, elements such as:
A sense of speed.
Sharp response.
Pleasant sound.
These are attractive features.
On the other hand, for daily use, characteristics such as:
Less fatigue on long journeys.
A sense of security on highways.
Comfort for passengers.
Smooth operation.
These are also important.
Therefore,
Feeling fast = superior.
Not feeling fast = boring.
Such a simplistic evaluation cannot be made.
Sports cars and luxury sedans inherently aim for different qualities of driving.
Main elements that create "perceived speed"
To summarize, the elements that make a car feel fast include:
Magnitude of acceleration.
Initial onset of acceleration.
Throttle response.
How torque is delivered.
Visual optic flow.
Seating position.
Engine sound / exhaust sound.
Wind noise.
Vibration.
Steering response.
Vehicle movement.
And so on.
In other words,
A single component.
A single numerical value.
Does not solely determine perceived speed.
Humans combine multiple sensory inputs to determine "this car is fast."
Quantifiable performance is also important.
While I've explained "perception" up to this point,
That doesn't mean the numbers are meaningless.
Rather,
0-100 km/h.
Maximum output.
Maximum torque.
Power-to-weight ratio.
Braking distance.
Lateral acceleration.
These are important for objectively comparing car performance.
On the other hand,
Sound.
Response.
Smoothness.
Sense of unity.
Naturalness of operation.
These are different evaluation criteria.
Next Science also, in existing articles, suggests the idea that "both numbers and perception are important, and they evaluate different things."
The important thing is not which is correct, numbers or perception, but to distinguish what is being evaluated.
"Driving Quality" as envisioned by Next Science
When it comes to car performance,
Horsepower.
Torque.
Top speed.
Such numerical values often attract attention.
However, when drivers actually evaluate a car, they also perceive elements that are difficult to express solely through numbers, such as:
The immediate response when the accelerator is pressed.
The naturalness with which the car moves forward.
A sense of unity with steering operation.
Vibration and sound.
The feeling of grip transmitted from the tires.
Next Science approaches this domain from the perspective of "driving quality."
However, the perceived feeling also changes depending on the car model, tires, road surface, driving environment, and driver.
Therefore,
Rather than assuming that "if it felt better, the performance definitely improved,"
It's important to separate objective performance evaluation and the feeling the driver perceives.
Summary: The "speed" a person perceives is created by the five senses.
The actual speed of a car and the speed a driver perceives do not always match.
This is because humans do not perceive speed solely by the numbers on the speedometer.
Acceleration.
Change in acceleration.
Throttle response.
Vision.
Sound.
Vibration.
Seating position.
Steering response.
A variety of information is received simultaneously.
Therefore,
There are cars that are exciting even if they are not very fast.
And there are cars that feel calm even if they are very fast.
This is where the fun of cars lies.
Even two cars with similar numbers in the catalog can feel completely different when actually driven.
This difference is created by the "driving feel," which includes human senses.
When comparing cars,
Don't just look at "how much horsepower it has" or "how many seconds it takes to go from 0-100 km/h."
Also pay attention to "how the car reacts when you press the accelerator," "how sound and vibration are transmitted," and "how you perceive speed."
This will reveal the car's character from a different angle than just the numbers.