The Engineering Core

Turning Off Regen Won’t Save Your Back Seat: The Real Physics of EV Car Sickness


Five seconds. That is roughly the period of the motion your stomach handles worst: a slow forward-and-back sway at about 0.2 Hz. In one lab study, 12 out of 12 highly susceptible volunteers hit moderate nausea at 0.2 Hz, compared with 8/12 at 0.1 Hz and 7/12 at 0.4 Hz.

Now picture a right foot in stop-and-go traffic: lift, press, lift, press. The usual advice is “turn regen down and the back seat will stop feeling sick.” Our new video argues that advice misses the point, and the physics supports it. Regenerative braking is one way to make a nauseating motion signal. Friction brakes, a twitchy throttle foot and a very quiet cabin can all do it too.

What’s Really Going On: A Prediction Error

The most widely used explanation of motion sickness is sensory conflict (Reason & Brand, 1975; Oman, 1990). Your inner ear senses motion: the otolith organs pick up linear acceleration and the semicircular canals pick up rotation. Your eyes, fixed on a cabin that isn’t moving relative to you, or on a phone, report that nothing is happening. When what the brain expects doesn’t match what it senses, nausea can follow.

That also explains why the driver almost never gets sick. In a classic yoked-pair experiment, people who controlled a nauseating rotation reported significantly fewer symptoms than partners who took exactly the same motion passively (Rolnick & Lubow, 1991). The driver’s brain gets a copy of every pedal command before the car moves. The rear passenger gets only the result. The video calls this “false smoothness”: the drive feels smooth from behind the wheel, while the back seat takes every correction with no warning.

To be fair, regen isn’t innocent. In an on-road study with 16 susceptible passengers, a high regen level caused more motion sickness than a low one (Xie et al., 2025). The real question is what regen does to the acceleration signal, and whether switching it off actually removes that signal.

The Engineering Mechanism

1. Jerk: how fast the push changes. Jerk is the rate of change of acceleration, j = da/dt, measured in m/s³. Take one target: 0.15 g of regen deceleration (≈1.5 m/s²). If you snap off the pedal and get there in 0.3 s, the average jerk is about 4.9 m/s³. If you ease off over 1 s, it drops to about 1.5 m/s³. The deceleration is the same, but the onset is roughly 3× gentler (our own worked arithmetic). A 2026 on-road study of Kia EV6 regen profiles used ramp jerks of 0.071 to 0.667 g/s (Kim et al., 2026).

2. Torque ramp and one-pedal tuning. An electric motor delivers torque within milliseconds. As the video points out, a gas car’s torque converter, engine revs and brake hydraulics add a small lag that smooths out a shaky foot. In an EV, how smooth the ride feels depends on how the automaker maps pedal travel to regen torque and how fast it lets that torque ramp. Turning regen off doesn’t remove the jerk. You just move it to your brake foot, and the video argues an untrained foot on friction brakes can be less smooth than computer-controlled linear regen.

3. Low-frequency fore-aft oscillation. ISO 2631-1’s motion-sickness weighting focuses on roughly 0.1–0.5 Hz, and fore-aft studies find nausea peaks near 0.2 Hz (Golding et al., 2001). A lift-press cycle every few seconds lands right in that band. That is our engineering inference; we haven’t seen it measured in a production EV.

4. Missing engine cues. In a gas car, rising revs warn you that a push is coming. EVs are quiet. In a lab sled test, audio cues given 1 s before each movement lowered sickness ratings (Kuiper et al., 2020), and Xie et al. found audio motion cues helped under high regen. On a test track, however, vibrotactile cues cut symptoms by about 40% while audio cues did less (Reuten et al., 2024). Promising, but not settled.

5. Heavy battery, firm chassis. The video also blames EV mass, stiffer suspension and flat cornering. How much a firmer ride adds to nausea, rather than discomfort, is less clear (see below).

⚡ Key point

Car sickness isn’t an on/off switch for regen. It comes from the shape of the acceleration signal (jerk and rhythm) combined with how much warning the passenger gets. You can make that signal worse or better with regen on or off.

What Drivers Can Actually Do

  • Treat the pedal like a rubber band. The video’s first habit: don’t let the pedal snap back. Take about a second to ease off. As the numbers above show, that is a direct cut in jerk.
  • Slow down before the corner, then hold a steady pedal. The video’s second habit: finish braking on the straight and keep the pedal still through the bend, so passengers never get a fore-aft tug on top of the sideways load.
  • Give the back seat some cues. The video’s third habit: fresh airflow on the face, eyes on the road ahead instead of a screen, and possibly the car’s simulated drive sound. A forward view helps in cars (Griffin & Newman, 2004), and airflow reduced visually induced sickness in one lab study (D’Amour et al., 2017).
  • Don’t switch regen off by reflex. If you drive it smoothly, the video argues full one-pedal driving can be comfortable for the back seat.

🔍 To verify

  • How strongly jerk alone predicts nausea, as opposed to comfort. Kim et al. note their stronger deceleration findings were not tied to larger jerk.
  • Whether firm EV suspension and higher-frequency vertical jolts directly cause nausea. The classic research points mostly to lower frequencies.
  • The video describes cool airflow calming nausea through a trigeminal–vagal pathway as “well-documented.” The benefit has lab support, but one later study reportedly didn’t replicate it, and I didn’t verify the mechanism.
  • Whether production “simulated drive sounds” work like the anticipatory cues used in research.

▶ Watch the Full Breakdown

The video covers why the vestibular system triggers nausea, why jerk (not speed or raw acceleration) is the problem, how battery weight and suspension add to it, a quick driving-mistakes quiz, and the three habits in detail.

📺 Why EVs Cause Car Sickness (It’s Not Just Regen Braking!) | The Physics of EV Motion Sickness

If you like engineering explained with numbers rather than hype, more videos like this are on The Engineering Core on YouTube.

Related reading: Why EVs Make You Motion Sick: An Electrical Engineer Breaks Down the Jerk & Control Loop Conflict

Sources

  1. Reason, J.T. & Brand, J.J. (1975). Motion Sickness. Academic Press.
  2. Oman, C.M. (1990). Motion sickness: a synthesis and evaluation of the sensory conflict theory. Can. J. Physiol. Pharmacol. 68, 294–303.
  3. Golding, J.F., Mueller, A.G. & Gresty, M.A. (2001). A motion sickness maximum around the 0.2 Hz frequency range of horizontal translational oscillation. Aviat. Space Environ. Med. 72(3), 188–192. PubMed
  4. Rolnick, A. & Lubow, R.E. (1991). Why is the driver rarely motion sick? The role of controllability in motion sickness. Ergonomics 34(7), 867–879. PubMed
  5. Xie, W. et al. (2025). Exploring the effects of regenerative braking and the auditory cues for alleviating motion sickness in electric vehicles. Int. J. Hum.–Comput. Interact. 41(24). DOI
  6. Kim, S., Yang, J., Hong, S.K. & Altinsoy, M.E. (2026). Vestibular time constant and individual susceptibility to motion sickness in real-world driving. Scientific Reports. Link
  7. Kuiper, O.X., Bos, J.E., Diels, C. & Schmidt, E.A. (2020). Knowing what’s coming: Anticipatory audio cues can mitigate motion sickness. Applied Ergonomics 85, 103068. DOI
  8. Reuten, A.J.C. et al. (2024). Anticipatory cues can mitigate car sickness on the road. Transp. Res. Part F 105, 196–205. DOI
  9. Griffin, M.J. & Newman, M.M. (2004). Visual field effects on motion sickness in cars. Aviat. Space Environ. Med. 75, 739–748.
  10. D’Amour, S., Bos, J.E. & Keshavarz, B. (2017). The efficacy of airflow and seat vibration on reducing visually induced motion sickness. Exp. Brain Res. 235, 2811–2820. PubMed
  11. ISO 2631-1:1997. Mechanical vibration and shock — Evaluation of human exposure to whole-body vibration (motion-sickness frequency weighting Wf).