No, Your EV Doesn’t Regen “All The Power” Going Downhill

For some reason I hear this from a little number of folks out there whenever I speak about performance in mountainous areas. "Mountains do not matter since you regen all the power going down." Here's the reality: it will always be less efficient to drive on sloping terrain since it will always take you more energy to go up the hill than you can recover going down. To prove it I snagged a Polestar 2 and went on a drive.

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24 responses to “No, Your EV Doesn’t Regen “All The Power” Going Downhill”

  1. @djp1234 Avatar

    It would if they used supercapacitors for regen

    1. @dylanluhowy Avatar

      Nope. Thermodynamics.

    2. @EVBuyersGuide Avatar


    3. @charname-player Avatar

      Nope, simple high school physics

    4. @djp1234 Avatar

      @@dylanluhowy what about using some kind of wind up spring, like in toy cars?

    5. @djp1234 Avatar

      @@charname-player never had that lesson in physics class. Never seen it tested. There’s no data.

  2. @emoney9931 Avatar

    I never give grief over passing on the right because really it’s the people in the left lane that aren’t doing their job of getting back over after passing.

  3. @rightlanehog3151 Avatar

    Alex, Are you absolutely certain we can handle the truth? 🤔

  4. @ALMX5DP Avatar

    Interesting results. I would have anticipated slightly better from the hillclimb relative to the flat driving but no denying the results. I just figured that the relative efficiency of an EV partially related to the percentage of time/distance it spent in regen and that is why EPA city drive cycles yield better efficiency numbers than highway most of the time (aside from average speed which of course affects aerodynamics and drag).

    1. @wolfgangpreier9160 Avatar

      Its a polestar, one of the most inefficient vehicles on the market. Try the same with a Ioniq or a ID.4.

    2. @ALMX5DP Avatar

      @@wolfgangpreier9160what does that have to do with the point of my comment? I was speaking about relative efficiencies.

    3. @wolfgangpreier9160 Avatar

      @@ALMX5DP Yes, exactly my point. relative efficiencies are always worse if the driving efficiency is bad.

      They use the same electronics, cables, software, batteries, connectors.

      If they do not want to achieve highest efficiency when driving the car, they put even less effort into highest efficiency while braking it.

    4. @ALMX5DP Avatar

      @@wolfgangpreier9160 I’m not sure what you mean. This specific vehicle got pretty decent efficiency when driving on level ground. That was my reference point when I commented about how inefficient the hillclimb and decent combination was.

    5. @nc3826 Avatar

      Resistance increases ‘logarithmically’ squared in terms of aerodynamics (Which you downplay)… Plus why are you assuming that the regen efficiency will be the same for a hilly versus city driving? since regen should be more efficient in the city…. and driving on hilly roads versus flatter highway roads Is also a factor….

      You have to be cautious, when you’re extrapolating…..

  5. @jenesuispasbavard Avatar

    Polestar gang. Side note: I absolutely love the regen braking on the Polestar 2 – perfect transition from regen to friction brakes at low speeds, and even when the battery is full or cold, it’ll apply the same amount of friction brakes in one-pedal mode as when there is more room for regen; so deceleration remains consistent.

  6. @FancyaBevMate Avatar

    It’s called perpetual motion and the holy grail of energy if you go equal from going up 😂 it’s Against the Laws of Physics

  7. @jenesuispasbavard Avatar

    Btw the little power meter on the dashboard will be white if using regen, or a sliver of hatched orange at the left end when the friction brakes are engaged.

  8. @JamesM-hb2cj Avatar

    I would be curious how close to a “perpetual motion machine” an EV could hypothetically be. Obviously not in real world driving, but I’d love to see a video where you drive 0-10mph, and then regen back to 0, and do that for about a mile and calculate efficiency. How close to 1000 mile range could it get? Again, irrelevant in the real world where you have to maintain speed and don’t spend equal amounts of time accelerating and decelerating, but would make for an interesting video.

    1. @Anothernerdyloser314 Avatar

      That’s not how that works at all… You’d get more range just maintaining a set 10mph than what you’re describing. Regen doesn’t add miles to your range. It just gives you back ~90% of what would have been lost to heat with friction brakes.

  9. @stargate25645 Avatar

    I feel like there were better things to test out than something that should be common sense.

  10. @frankdeboer1347 Avatar

    I don’t get the love for one pedal driving. You can use the brake pedal to regenerate and feel in control of your vehicle. I love my brake pedal on my Ford plug-in hybrid.

    1. @frankdeboer1347 Avatar

      I like that you drive it just like a regular car while getting the benefits of regeneration.

    2. @ALMX5DP Avatar

      Kinda feel the same way. If the vehicle is tuned right I like having the accelerator just control acceleration and the brake pedal to control deceleration (using regen and then friction brakes if needed).

  11. @gregkramer5588 Avatar

    No magic, no 100% efficacy!

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