Speed will make accidents worse (deadlier). Acceleration will make accidents more likely. Sports cars flooring it from a stop, losing traction and hitting a telephone pole is like a whole genre of YouTube videos.
Acceleration does not make accidents more likely (well, technically, without the ability to accelerate, it'll be impossible to have a car crash, I guess?). Risky behavior makes accidents more likely. Not being able to control your machinery and still trying to push it to its limits makes accidents more likely. Here the problem is people who behave anti-social and ego-centrical. But that's behavior we like to generally encourage and then fix it by adding regulations around the most stupid things.
> Sports cars flooring it from a stop, losing traction
Traction control prevents this these days.
It still happens, of course, because idiots WANT to spin their tires and so turn off the traction control. But spinning tires != going fast. Usually sports cars flooring from a stop are interested in speed, not tire smoke, so the TC is still on.
That said, I know in my Model 3 Performance, I've floored it from a traffic light in the rain and had very little spin. It's insane how effective traction control is in an EV.
It is not the speed that kills, but the sudden deceleration hitting a tree.
Joking aside, acceleration can be a real problem. I ride a lot my motorcycle to work, shopping etc. I am closing to an intersection, I see a car that has to yield and when I am close enough, I am pretty sure I will not be hit even if the car is not yielding, which happens quite often (many drivers don't see motorcycles or ignore their rights). With a very high acceleration, the risk of getting hit is a lot higher.
This is an interesting question. If you’re accelerating and take your foot off the gas pedal, the car continues to accelerate until braking is applied. So if you accelerate very quickly to the speed limit, there would be a likely situation where you pass the desired speed unless you get on the brakes, which requires reaction time.
But yeah - I don’t necessarily agree with regulating it away for safety - people need to have personal responsibility. But regulations could make car companies optimize for other variables though (like distance and economy) which could be good.
I have procrastination mode on my account so I needed to create another account to respond.
Re-reading that, I didn’t write very clearly - and thankfully my car doesn’t require braking to stop accelerating indefinitely.
What I meant was, in a combustion engine, there is still some acceleration that occurs as the engine drops from 6-7k RPM down to idle. If you’re running acceleration from 0-60 in 2 seconds, that continued acceleration after you take your foot off the gas and the engine runs down to idle may be another 10 mph. In my experience, acceleration for a combustion engine to hit its best time is usually pedal to the metal and isn’t a smooth stop at that exact top speed (which would require letting off the gas ahead of reaching the top speed so you don’t overshoot).
In context of the parent and regulating speed vs acceleration, my point was that fast acceleration can lead to people overshooting the intended speed / speed limit.
That said, power delivery for electric motors (that would be in the 2-3 second 0-60 range) may not have this ramp-down period, so acceleration would stop immediately (and maybe slow down aggressively with regenerative braking).
> there is still some acceleration that occurs as the engine drops from 6-7k RPM down to idle.
Not in any vehicle I've operated. The moment I pull off the throttle completely, it stops flowing any more than idle speed fuel mixture into the motor. Without that combustion power, it starts to act more like an air compressor almost immediately, causing negative force output. It is taking energy from the crank to try and compress a mixture which, when combusted (if even combustable, most likely not), results in less expansive force than the force it took to compress. This is even more pronounced at high RPMs as that action happens more times every second.
If I let go of the throttle on my motorcycle at 9krpms and like 70mph or whatever it feels like I pressed hard on my rear brake instantly, for all intents and purposes. You'll feel your weight get thrown forwards immediately.
If your car continues to accelerate after you've taken your foot off the gas something is wrong with your car.
If you take your foot off the gas, acceleration should effectively stop, right? F=ma, so with mass held constant and the only forces being friction, a is actually slightly negative. So max speed happens as soon as you release the gas pedal.
I'd love to delegate that part of driving to my car. Automatically maintain speed limit (+5 mph or so, or I'll be tailgated the whole way home) and following distance to the car in front of me. I'll just cover the brake and tap it if I see something wrong in front, at which time it can revert to manual speed control.
Bonus points for maximum performance acceleration without overshoot to the speed limit if I am the first one stopped at a red light when it turns green.
Adaptive cruise control is awesome, but the implementations I've used are unaware of the road's speed limit.
1. Low speeds, the car will accelerate a bit to where it moves at idle speed. (Usually very slow. Like 2-3 MPH.)
2. High speeds: If you lift off the accelerator, the car will slow down. In a manual transmission car, this slowdown is much more pronounced, and can often be used instead of the brakes in non-emergency slow deceleration conditions. In an automatic the slowdown is less, but still there.
To be fair, the car is accelerating, just accelerating in a direction opposite from the current forward movement, resulting in a decrease of the vehicle's current speed.
Probably not what they meant in that comment though.
