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Comment by 6DM | Hacker News Reader

I imagine that getting a heavier car up to speed in stop and go traffic would be more energy intensive. Also driving it uphill has to use up a lot more battery since it's so much heavier. The weight reduction should improve [1] tire longevity and reduce maintenance costs. Overall I think it could help with range and costs so it seems like a worthy thing to focus on.

[1] - https://arstechnica.com/cars/2022/12/heres-why-electric-vehi...

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Yeah weight also has all sorts of knock on effects on other components. Suspension, tires, brakes, frame all need to get beefed up for extra weight and/or wear quicker.

Unless it's a steep grade you'll recoup a lot of that uphill energy going down hill. The energy used going up the hill is just stored potential kinetic energy.

Regen efficiency is nowhere near 100% though. You still lose a lot due to friction/conversion losses/etc.

You don't need to do regen to get that energy back. Your car gets significant air and rolling resistance going down the highway, its having to put in energy to keep the car going 40+mph. Using that stored kinetic energy of just going down the hill is extremely efficient so long as you're not having to do any braking, which unless you're rolling down a mountain you probably don't need to "ride the brakes". Hence my "unless its a steep grade".

The energy does not need to go back into the battery. It offsets the energy needed from the battery to keep the car going at speed.

Regen efficiency makes no difference in most hills, because you probably won't be using the regen for it.

Regen breaking should in theory help mitigate that. A lot of that energy is recaptured when you slow down. Heavier vehicles have more energy to recapture, assuming the drive train is up to it.

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