3 ms·

I’ve heard this many times, but I’ve never actually seen it cited.

MrRadar 5y ago
It's the reason why vehicles have a separate "city" and a "highway" fuel economy rating, since the former takes into account the expected stopping and starting you do in city traffic which you would not on an uncongested highway. It also makes intuitive sense if you understand physics: in a non-hybrid ICE vehicle, you impart energy from the engine into the wheels to accelerate the vehicle and you impart energy from the wheels into the brakes to decelerate, effectively wasting the original energy from the engine as heat. In hybrids and EVs some of that energy can be recovered by using the motor as a generator to recapture it in a useful form.
hobs 5y ago
It's just basic newtonian physics, it takes energy to start and stop moving and a lot less to keep doing what you are doing.
- deleted 5y ago
  [deleted]
- bushbaba 5y ago
  Wouldn't it be more-so that with ICE vehicles you loose 100% of the kinetic energy as heat when stopping. With an EV you convert a portion back to the battery packs with regenerative breaking.
  - hobs 5y ago
    Correct, though many times costs are not just fuel - total ROI includes service cost, availability of replacement parts, insurance costs, etc - a NG car could cost more in fuel and still be cheaper for effectively forever depending on how the books land.
nomel 5y ago
Not trying to be rude, but it's because it's intro Physics (F=m*a, with F coming from fuel, battery, or brakes), with an understanding that the process that generated that force has an efficiency that's less than 100%, mixed with a dash of intro Calculus (integral of force).
- l33t2328 5y ago
  Respectfully, intro physics mentions nothing about ICE operating most efficiently at 50 MPH.
renewiltord 5y ago
Here's a couple of good ones - https://sci-hub.se/https://doi.org/10.4271/2017-01-9379 https://sci-hub.se/https://doi.org/10.4271/2017-01-9379. - https://sci-hub.se/https://doi.org/10.4271/2013-01-1113 https://sci-hub.se/https://doi.org/10.4271/2013-01-1113 You'll want the second just to compare different speeds. Nice pretty graph to follow.

It's the reason why vehicles have a separate "city" and a "highway" fuel economy rating, since the former takes into account the expected stopping and starting you do in city traffic which you would not on an uncongested highway. It also makes intuitive sense if you understand physics: in a non-hybrid ICE vehicle, you impart energy from the engine into the wheels to accelerate the vehicle and you impart energy from the wheels into the brakes to decelerate, effectively wasting the original energy from the engine as heat. In hybrids and EVs some of that energy can be recovered by using the motor as a generator to recapture it in a useful form.

hobs 5y ago

It's just basic newtonian physics, it takes energy to start and stop moving and a lot less to keep doing what you are doing.

deleted 5y ago
[deleted]
bushbaba 5y ago
Wouldn't it be more-so that with ICE vehicles you loose 100% of the kinetic energy as heat when stopping. With an EV you convert a portion back to the battery packs with regenerative breaking.
- hobs 5y ago
  Correct, though many times costs are not just fuel - total ROI includes service cost, availability of replacement parts, insurance costs, etc - a NG car could cost more in fuel and still be cheaper for effectively forever depending on how the books land.

nomel 5y ago

Not trying to be rude, but it's because it's intro Physics (F=m*a, with F coming from fuel, battery, or brakes), with an understanding that the process that generated that force has an efficiency that's less than 100%, mixed with a dash of intro Calculus (integral of force).

l33t2328 5y ago
Respectfully, intro physics mentions nothing about ICE operating most efficiently at 50 MPH.

renewiltord 5y ago

Here's a couple of good ones - https://sci-hub.se/https://doi.org/10.4271/2017-01-9379 https://sci-hub.se/https://doi.org/10.4271/2017-01-9379. - https://sci-hub.se/https://doi.org/10.4271/2013-01-1113 https://sci-hub.se/https://doi.org/10.4271/2013-01-1113 You'll want the second just to compare different speeds. Nice pretty graph to follow.