Zero to sixty in 2.5 seconds is fun, no doubt about it, but it is fun on a racetrack. You can go on YouTube right now and find dozens of people utilising Tesla's existing "ludicrous mode" on public streets.
And here's the thing, if people want to endanger their own lives that's fine. But they aren't just endangering their own lives, they're also endangering both other road users and pedestrians (when they eventually lose control).
I don't think anything has been done about this yet because Teslas are still pretty uncommon, and the features which unlock "ludicrous mode" are even more uncommon (like 1% of 1%). But once electric vehicles are the norm and the body count racks up, we'll see legislative action.
As an aside you could tie maximum acceleration into road conditions, including lowing it if the road is icy or wet, or increasing it on surfaces that provide superior grip (like freeways).
first of all, a minivan can kill you doing 10mph.
second, cars with this much power (and more importantly, top speed), have been around for a long time. you can build an 8-second quarter mile car in your garage and drive it on the street.
more nanny-state nonsense. "think of the children".
I really think it boils down to that some people value their own personal enjoyment over other people's safety. The sad truth is that you could absolutely enjoy vehicles like that but without endangering safety, by going to a race track. There's literally race days even for road-legal vehicles.
Electric vehicles are going to take something, once rare, and make it common. Once it becomes common, the accident incidents will be more than just statistical noise, and legislative action may follow.
The NHTSA and FMCSA are currently working on a proposal for large commercial vehicles that would artificially limit their maximum speed to 68 mph. So it isn't unheard of for legislation to be created to target new vehicles which aims to improve public safety.
Velocity is a much more obvious policy knob to tune for the goal of less vehicular deaths and injuries.
Similarly, in most places, speed limits are actually a little lower than they would be in the ideal world where everybody obeys them, to account for the fact that most people actually go a bit over the speed limit. And there are still highways that have absurdly slow speed limits that date back to the 1973 oil crisis (federal law set a maximum speed limit of 55mph, and not all highways have recovered from that yet).
Driving while eating a cup noodles is extremely dangerous too, I don't see any laws on the books against that.
EDIT: Thank you for the replies!
So, in a future where Tesla's are all over the roadways,and the earth falls under alien attack or some other crisis -- he could easily escape by speaking to any nearby Tesla, which would give him full access (maybe even unlocking faster speeds ;). Perhaps even having some sort of transponder to send the nearest Tesla's to his rescue, should that be required.
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[0] - Why ground assault instead of orbital bombardment? Well, there aren't many alien vessels left in orbit after a massive onslaught of Falcon 9s and BFRs ;).
I'd bet they have been slowly improving their junction temp. estimation model and are now able to push the power semiconductors a little bit closer to their temperature limit, allowing them to produce more current (or the same current for a longer duration) before pulling back.
> Speeds like this offer more Gs than Earth, so the rate of acceleration is faster than falling. It can feel difficult to support your head and shoulders if you don’t lean back on the headrest.
So while it will be great to "hoon about" in and should be a win at the traffic light gran prix there are probably much better track day cars.
... and here they defined it so the P100D is the fastest. Welcome to the tautology club.
Meanwhile, Wikipedia has three cars above the P100D on its quickest 0-60 list: the Porsche 918, the LaFerrari, and the Bugatti Veyron.
https://en.wikipedia.org/wiki/List_of_fastest_production_car...
Note also that Tesla has also been called a bit "optimistic" with their 0-60 times as compared to other manufacturers (e.g. by Top Gear when testing P90D against Audi RS6 this year).
You're not the target audience for their top-of-the-line P100D. It's aimed at people who would otherwise buy Bugatti Veyrons, Ferraris, etc., and range probably doesn't even come up in their decision making process. The Veyron has a range of 50 miles at top speed, for example.
More like Porsche 911 Turbo, Mercedes SLS, Audi R8 buyers.
The people buying Veyrons are doing it for status. They're not going to replace their >$2 million car with one <$2 hundred thousands.
That top speed being 250mph. Who drives 50 miles at 250mph? And where do they do it?
And, more importantly, they can refill in the blink of an eye and travel 50 more.
People in the market for supercars at up to $2MM are not in the same market as the P100D.
Range may not come up as an issue, as you say with the Veyron. The fact that the Veyron can actually accomplish it's top speed for those 50 miles will, however. Just like Tesla cannot complete a lap of a race course at top speed without thermal shutdown / limiting.
1. No cold starting. The engine is on as soon as you push power in.
2. Equal torque at all speeds
3. The lack of a need for a transmission. All "gears" can be controlled by how much power you're feeding
Low mass connected to the wheels(aside from the stator) combined with near instant torque control means they can adjust power to the wheels in a sub-ms(supposedly) range. Once you break traction it's really hard to get it back and you're fighting the momentum of an ICE engine in the non-EV case. You also have two completely independent motors so you don't have to fight with any transfer case or torque converter and it can just instantly shift power to where traction is available.
All I know is I can floor our 85D in the rain and it doesn't even shimmy, just plants and takes off.
With ICE, you have to choose either power or efficiency, i.e. the engine is tuned for specific load and the efficiency sacks when heavily under loaded. (Constant legal-speed driving makes only a fraction of load of heavy acceleration.)
But you still have to make tons of power and not be too heavy of course.
"A hard slap on the face may impose hundreds of g-s locally"
"Early experiments showed that untrained humans were able to tolerate 17 g eyeballs-in (compared to 12 g eyeballs-out) for several minutes without loss of consciousness or apparent long-term harm" https://en.m.wikipedia.org/wiki/High-G_training
> The terms "eyeballs in" "eyeballs out," and "eyeballs down" correspond to acceleration fields AX, -Ax, and AN, respectively, where AX, -Ax, and AN refer to the direction of acceleration forces measured in the conventional airplane body-axis coordinate system.
> AN acceleration factor, ratio of acceleration force to weight, positive when directed upward along spinal axis (i.e., from seat to head )
> AX acceleration factor, ratio of acceleration force to weight_ positive when directed forward transverse to spinal axis (i.e., from back to chest)
(o) https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/199802...
But even lower accelerations will glue you to the seat because gravity acceleration affects every part of your body. Where as the car grabs you by the butt and yanks you forward.
So - I think he has probably some vague idea of Newtonian physics but just didn't manage to produce coherent sentence.
The feeling of weight we associate with gravity is not distinguishable from elevator-style or car-style acceleration (not counting vibrations; or tiny gradients in the field). You don't feel gravity gluing you to the ground, you feel the ground continuously shoving you skyward to stop the free fall.
See: equivalence principle https://en.wikipedia.org/wiki/Equivalence_principle
And Tesla only compares with cars currently in production. The LaFerrari and 918 are not.
Definitely some definitional tweaking to get the "right answer," but not quite a tautology.
http://www.caranddriver.com/features/tesla-model-s-p85d-at-l...
http://www.caranddriver.com/flipbook/lightning-lap-2016-ever...
Your argument is comparable to banning sharp knives because someone started selling them cheaper than butter knives. Both types have always been sufficiently available and dangerous that making one more common than the other isn't going to change anything
At the supercar level, you can basically assume infinite power when looking at acceleration in the lower speed ranges. The limit is traction, not torque. A sufficiently strong EEV can continuously max out traction. An ICE supercar does the same, but with a few tiny gaps for shifting that add to the total time. The ICE supercars do not need a stronger engine to come closer to the Tesla, they need faster transmissions to minimize shifting gaps. I think that this is also the prime reason why manual transmissions are disappearing/have disappeared from supercar territory, dual clutch automatics provide shorter gaps.
Edit: why the downvotes? It's well documented that the P90D is no quicker than a Civic Type R around a proper racetrack.
That said, most aren't in a position to really push their cars, and they don't... It's mostly bragging and any car with a 0-60 under 5 seconds will give a lot of that fun.
on second thought, never mind, i probably know your answer.
"ban everything dangerous until there's no possible way anyone can get hurt" is not what freedom is.
that seems like a good way to increase road fatalities
but don't let that stop you from passing 20 more laws, and then banning people from driving altogether after you realize that, as it turns out, criminals don't follow the law.
which is already happening, just look at the autonomous driving effort. which i'm sure makes you very happy. soon, nobody will drive, we will all be living in a perfect harmonious utopia of robotic sentience.
I think the better metric is the number of deaths per billion vehicle-km. In your metric most European countries have half the deaths than the US, but it's mostly explained by the fact that we drive less. I guess people had fewer cars and drove less in the 1930…
EDIT:
I found the stats: in 1930 you had 15.12 deaths per 100 million miles vehicle, in 2014 1.08. So the reduction is not 2.5x, but 15x!
Don't assume that everybody will.
I guess the question is where the line is drawn between sensible and "nanny-state" regulation.
Also if you can get someone who has a lot of experience with motor control they can get you going pretty quickly. I'm assuming what's in the Tesla is a brush-less DC motor and there are a few things you can do (especially since you're on some serious batteries in the Tesla) to push some serious torque at the startup curve. You're probably only running a modulated power start for a few seconds. After the first few seconds you're shoving the full amperage into the motor.
You are right about the startup torque. AC induction machines can produce full breakdown torque at zero speed, but this does require high current (but luckily not high power because the applied voltage is still low due to low motor speed).
Another limit is the junction temperature of the power semiconductors in the inverter(s). I think Tesla uses liquid cooled inverters, but this typically means there isn't much mass to act as a heatsink (relying on the liquid coolant instead), so overload times are typically very short. I'd would guess this is actually the limit in their design. In other words they can put very high currents into the motor for a long period of time before it thermally overheats, but way before that time they have to reduce the current in order to protect the power semiconductors in the inverter.
For a much better explanation than I can provide, see https://en.wikipedia.org/wiki/Power_band#Electric_Motors
Also if anyone wants to see someone do a full on heavy run of the Veyron check out Ben on Goldrush 2015? He ran his I think to 255mph if memory serves me right...
The _current_ 0-60 time, you mean. Especially with this:
"And Tesla only compares with cars currently in production."
considering this is only a teaser tweet, there's a slight hint of irony there. "Currently in production" is also very different from "fastest production cars". Very selective.
This happened last time Tesla announced something like this - people fell over themselves to install it in the Wikipedia page for fastest production cars. Even though it was: 1) not yet available, 2) not verified, and 3) described even by Tesla themselves as an "expected result". i.e. a press release.
When that didn't work, they took to the page to add a new column to the list of accepted results, to add, effectively "manufacturer projected results", with the end result looking entirely silly and forced - a top 20 chart with Tesla being the only one to have a result in a "not real, not yet" column.
And I see no irony. The teaser tweet is stated using the future tense. It will be the fastest car in production once it comes, unless some other car maker has a big surprise between now and then.
As for the Wikipedia stuff, I offer no defense of it, but I'm not surprised. Wikipedia suffers from plenty of fanboyism.
But it's not the biggest thing in the world. :)
There's also the weird aspect that the car itself has been sold for months, they'll just become faster once the update hits.
Maybe there are still "a lot" of cars like that in the realm of million-dollar supercars. But I think it qualifies as crazy when the context is a family sedan that's fairly cheap to operate.
Edit - here's a more stringent discussion: http://physics.stackexchange.com/questions/75032/maximum-acc...
High school friction is wrong.
Source: various of my cars (in the past, I just have lame hybrids now) and a g meter
No, it's at least mostly correct. High school friction says
F = mu * W
If it's failed you, it's failed in failing to mention that the tire-road interface can have a coefficient of friction greater than one, and in failing to mention that the normal force can be increased with aerodynamic downforce.
Source: note all the people here who thought it couldn't be greater than one.
As long as the torque is lower than friction you should be fine.
Related: if you've ever wondered why some drag cars (e.g. Funny cars) have short exhaust pipes angled up and back, now you know.
The same kind of thing (not literally, but analogously) is already happening at the atomic level, giving the tires a coefficient of friction of more than 1.
I suspect what the OP was trying to get at is the vector addition of gravity plus the forward acceleration of the car means that the apparent scalar force feels substantially higher than normal (i.e. 1g downwards); it's just poorly worded.