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> But EVs are universally heavier than gas cars of equal dimensions thanks to their batteries, and many of them are already beyond the limit. And this definite

> But EVs are universally heavier than gas cars of equal dimensions thanks to their batteries, and many of them are already beyond the limit. And this definitely matters. The energy required to stop a vehicle is a linear correlation to the mass, and our ability to stop vehicles quickly still relies on creating heat using friction; it has not progressed nearly as quickly as our ability to accelerate vehicles.

brucethemoose2 3y ago
Even a junker can lock its wheels under hard braking, right? AFAIK the limiting factors are tire grip, ABS control and of course mass.
- MadnessASAP 3y ago
  I wouldn't assume that. I've definitely been in a few junkers that couldn't do it on warm, clean, and dry pavement. Although you've already got pretty good braking performance in those conditions anyways. Even then though, the travel of the brake pedal may be such that the time to full braking power is significant. Fortunately brakes are fairly straightforward and getting them back to good performance usually isn't a complex or expensive process.
conk 3y ago
Hybrids and EVs can also stop (to some extent) with regenerative braking.
snovv_crash 3y ago
That's not true, even in hard braking a large fraction of the kinetic energy is converted back via regen braking.
giantg2 3y ago
"and our ability to stop vehicles quickly still relies on creating heat using friction; it has not progressed nearly as quickly as our ability to accelerate vehicles." We've had a lot of innovation in braking - including better tire compounds, disc brakes, anti lock, better brake compounds and design, etc. Most people just don't talk about them or compare braking stats.
- falcolas 3y ago
  There have been some advances (fewer in recent years, most of the technologies you've listed are decades old), but braking distances for consumer vehicles is still in the 130' range at 60 mph. This is better than the 200' from a decade ago, but still significant. Consumer vehicles now able to accelerate to 60 mph in 2 seconds, but it can still take them up to 3 seconds to get back to 0. Note: These are based on a safety article from Edmonds, 'Keep your Distance', who uses a distance of 132' with a braking time of 3.1 seconds. They appear to be measuring a car at the lighter end of the spectrum, as other articles I found still refer to 200'+ at the heavy end of the spectrum.
  - giantg2 3y ago
    Many of the technologies I've listed are continually improved. They're not just a once and done, especially for things like compounds. Average braking distances for any passenger vehicle class isn't even close to 200 feet, not even for pickup trucks. https://www.consumerreports.org/cars/car-safety/best-and-worst-braking-distances-a2960086475/ https://www.consumerreports.org/cars/car-safety/best-and-wor... Many of the fastest cars also have the best brakes. There are a number of them that can even get under 100'. https://www.motortrend.com/features/20-best-60-to-0-distances-recorded/ https://www.motortrend.com/features/20-best-60-to-0-distance... If we want to talk trends in poor braking, we can look at Tesla and EVs in general. In many cases EVs select low rolling resistance tires with poor performance. The top quality low rolling resistance tires can be good, but many EVs have tight margins and lower end tires with less grip. It's not just weight. You can compare similar weight vehicles like a Tesla and a Silverado, and the conventional vehicle generally brakes better.

brucethemoose2 3y ago

Even a junker can lock its wheels under hard braking, right? AFAIK the limiting factors are tire grip, ABS control and of course mass.

MadnessASAP 3y ago
I wouldn't assume that. I've definitely been in a few junkers that couldn't do it on warm, clean, and dry pavement. Although you've already got pretty good braking performance in those conditions anyways. Even then though, the travel of the brake pedal may be such that the time to full braking power is significant. Fortunately brakes are fairly straightforward and getting them back to good performance usually isn't a complex or expensive process.

conk 3y ago

Hybrids and EVs can also stop (to some extent) with regenerative braking.

snovv_crash 3y ago

That's not true, even in hard braking a large fraction of the kinetic energy is converted back via regen braking.

giantg2 3y ago

"and our ability to stop vehicles quickly still relies on creating heat using friction; it has not progressed nearly as quickly as our ability to accelerate vehicles." We've had a lot of innovation in braking - including better tire compounds, disc brakes, anti lock, better brake compounds and design, etc. Most people just don't talk about them or compare braking stats.

falcolas 3y ago
There have been some advances (fewer in recent years, most of the technologies you've listed are decades old), but braking distances for consumer vehicles is still in the 130' range at 60 mph. This is better than the 200' from a decade ago, but still significant. Consumer vehicles now able to accelerate to 60 mph in 2 seconds, but it can still take them up to 3 seconds to get back to 0. Note: These are based on a safety article from Edmonds, 'Keep your Distance', who uses a distance of 132' with a braking time of 3.1 seconds. They appear to be measuring a car at the lighter end of the spectrum, as other articles I found still refer to 200'+ at the heavy end of the spectrum.
- giantg2 3y ago
  Many of the technologies I've listed are continually improved. They're not just a once and done, especially for things like compounds. Average braking distances for any passenger vehicle class isn't even close to 200 feet, not even for pickup trucks. https://www.consumerreports.org/cars/car-safety/best-and-worst-braking-distances-a2960086475/ https://www.consumerreports.org/cars/car-safety/best-and-wor... Many of the fastest cars also have the best brakes. There are a number of them that can even get under 100'. https://www.motortrend.com/features/20-best-60-to-0-distances-recorded/ https://www.motortrend.com/features/20-best-60-to-0-distance... If we want to talk trends in poor braking, we can look at Tesla and EVs in general. In many cases EVs select low rolling resistance tires with poor performance. The top quality low rolling resistance tires can be good, but many EVs have tight margins and lower end tires with less grip. It's not just weight. You can compare similar weight vehicles like a Tesla and a Silverado, and the conventional vehicle generally brakes better.