Volvo is introducing a 112mph speed limiter to all its new cars • Hacker News Board

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#251

Post by sliken » Tue, Mar 05, 2019, 6:04 AM UTC

mbell wrote: post #90

LyndsySimon wrote: post #43

Earlier quoted context omitted.

As I mentioned in another comment, tires with an "S" speed rating go to 112 MPH, while tires with an "H" rating go to 130 MPH. I'm guessing they either downgraded the factory tires or were concerned about lawsuits from owners who installed aftermarket "S" rated tires.

Lower speed rating also usually means lighter construction and a 'harder' compound, both of which reduce cost and improve fuel milage.

Actually it's the opposite I believe, at least for the same family of tires.

Sure there are high efficiency tires with harder compounds and are more efficient.

But if you get the sporty tire from whatever brand the higher speed ratings generally have the less flexible/harder material. The limiting factor being the heat generated from the flexing builds up. So generally a 150 mph rated tire gets less traction, costs more, and is worse when it's cold than a 112 mph rated tire.

So even on a fairly sporty car and tire you are best off getting the lowest rated tire that will accommodate your max speed.

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#252

Post by sliken » Tue, Mar 05, 2019, 6:12 AM UTC

batbomb wrote: post #29

MikeKusold wrote: post #7

Earlier quoted context omitted.

It's roughly 180 km/h. Your assumption of a 70mph speed limit is based on the US, and it's incorrect. Portions of highways in the US have 85mph speed limits (i70 on the eastern part of Utah comes to mind).

I've done 120 or 130 on the stretch between Wendover and Salt Lake City. Most people go about 90

Heh, yeah, that area is perfect for high speed driving. Mostly perfectly straight, good quality roads, and excellent visibility. There's an annual race in Nevada not too far from there (highway 318) that's the world's fastest road race. Last year someone average 219mph and was doing 4 wheel drifts at over 200 mph on the sharpest (almost straight at normal speeds).

Not bad for a normal highway.

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#253

Post by PostOnce » Tue, Mar 05, 2019, 6:21 AM UTC

georgebarnett wrote: post #245

PostOnce wrote: post #235

Earlier quoted context omitted.

How many auto fatalities are a result of people driving 150? Almost none, I'd wager. So then is my argument still ridiculous? Freedom has value. Just because we can force some people to do some things more safely in some cases doesn't mean we should always do it. Otherwise, we can just outlaw cars entirely and force everyone to only go places where rails take them at government-approved speeds.

Fortunately, somebody has actually studied this and has found that yes, speed does matter: "In Rheinland-Pfalz, a 130 km speed limit was also introduced on a 167km section of the A61 in 1991 and has been retained since then. This measure was combined with a ban on overtaking for heavy good vehicles. The impact of these two measures was a 30% reduction in fatal and severe injury accidents (comparing one year after and…

1] I'm not opposed to speed limits, I'm opposed to the car enforcing them even when there is an exceptional case it's unaware of.

2] You can drive super dangerous without driving super fast

3] Almost no one drives super fast

4] The same pdf also says the death rate is exactly the same on roads without speed limits as those with speed limits... but I assume we're going to ignore that part and other contradictory studies to drive your point home?

i.e. 67% of roads have no permanent limit, 67% of deaths occur there...

And then you'll say "yes but that doesn't take into account the traffic volume on those stretches of road"

and I'll point to something else, and it'll get old, and you don't appear interested in considering other viewpoints anyway.

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#254

Post by dmitriid » Tue, Mar 05, 2019, 7:01 AM UTC

flyingfences wrote: post #227

Johnny555 wrote: post #220

Earlier quoted context omitted.

That sounds like an unrealistic fantasy that's fun to watch in the movies, but not likely in real life. Driving 130mph in a storm or forest fire is more likely to result in you running off the road (or into another fleeing vehicle) than getting to safety. But if this is your fear, you should probably drive an off-road motorcycle so you have more options to get out of town when the disaster strikes, limiting yourself…

> not likely But it is an edge case.

These are not edge cases.

- In a forest fire or in a storm visibility is low, so you wouldn’t be able to drive at speeds over 112mph anyway (see any footage of people driving through forest fires).

- A tsunami’s speed doesn’t exceed 20-30 mph on land

- a pyroclastic flow moves at 100kmh (62 mph)

In any case these edge cases do not outweigh the lives (potentially) saved by capping a car’s speed.

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#255

Post by tropo » Tue, Mar 05, 2019, 7:23 AM UTC

dmitriid wrote: post #254

flyingfences wrote: post #227

Earlier quoted context omitted.

> not likely But it is an edge case.

These are not edge cases. - In a forest fire or in a storm visibility is low, so you wouldn’t be able to drive at speeds over 112mph anyway (see any footage of people driving through forest fires). - A tsunami’s speed doesn’t exceed 20-30 mph on land - a pyroclastic flow moves at 100kmh (62 mph) In any case these edge cases do not outweigh the lives (potentially) saved by capping a car’s speed.

Suppose the road leading you to safety is not direct. It is at an angle, for example 70 degrees away from the desired direction. You'll need to exceed 112 MPH to outrun that pyroclastic flow.

To escape the tsunami, you first have to drive down a road that runs along the beach. After doing that for a while, you may then turn onto a road that takes you away from the ocean.

Visibility is usually fine in a storm. Hurricanes have intermittent periods of severe rain and insignificant drizzle. Forrest fire visibility all depends on the wind direction, and is often fine if you aren't already surrounded.

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#256

Post by boznz » Tue, Mar 05, 2019, 7:27 AM UTC

oppositelock wrote: post #199

tiernano wrote: post #176

Earlier quoted context omitted.

Doesn't this stopping distance depend on the car? Said German cars have bigger breaks and bigger tyre surface and have been proven to stop quicker. Top Gear showed this often (Australian trip with the m6, Bentley and gtr) all stopping in less than half the Highway Code distance...)

Stopping distance does depend on the car, but physics has a bigger influence. The kinetic energy in a car is 1/2mv^2. No matter what car you're in, going twice as fast requires dissipating four times the energy in order to stop. So, take a sporty car with twice the braking performance of a basic car, and you can go 1.44x as fast as the basic car while still having the same stopping distance. I have a very light car t…

Reaction time has an even bigger influence. Slower speed = more reaction time

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#257

Post by dmitriid » Tue, Mar 05, 2019, 7:47 AM UTC

tropo wrote: post #255

dmitriid wrote: post #254

Earlier quoted context omitted.

These are not edge cases. - In a forest fire or in a storm visibility is low, so you wouldn’t be able to drive at speeds over 112mph anyway (see any footage of people driving through forest fires). - A tsunami’s speed doesn’t exceed 20-30 mph on land - a pyroclastic flow moves at 100kmh (62 mph) In any case these edge cases do not outweigh the lives (potentially) saved by capping a car’s speed.

Suppose the road leading you to safety is not direct. It is at an angle, for example 70 degrees away from the desired direction. You'll need to exceed 112 MPH to outrun that pyroclastic flow. To escape the tsunami, you first have to drive down a road that runs along the beach. After doing that for a while, you may then turn onto a road that takes you away from the ocean. Visibility is usually fine in a storm. Hurrica…

Too many “suppose”s.

At speeds over 100kmh (62 mph) you gain only 36 seconds or less per 10 kmh (6.2 mph) of speed increase per 10 km (6.2 miles) of distance.

So, you need to be in a dire situation, already traveling at top speed, on a road that doesn’t lead away from danger, where ~30 seconds of time would make a difference.

That’s a lot of ifs and edge cases.

When reality usually looks like this: https://youtu.be/coPW6unxeY8 (a three-point turn before tsunami) or this: https://youtu.be/7J6O4HkKxlo (driving through a forest fire)

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#258

Post by imartin2k » Tue, Mar 05, 2019, 7:48 AM UTC

rad_gruchalski wrote: post #230

imartin2k wrote: post #183

German here. I once drove an Audi A8 from Hanover to Berlin (while working for a car rental company). It was pretty much 250kph (155 mph) all the way (except where there was a speed limit of course). Definitely an insane experience. My hands were extremely sweaty. Yet I couldn't stop driving that fast. In that type of car, you don't really notice it anyway. But you DO notice it when suddenly another car is getting in…

You driven like that once, some people drive like that daily. Usually it’s not them causing accidents. Whatever, anyone can be fast in a straight line.

I didn't make a remark about accidents. The scenario I described (the sudden appearance of another car in your lane while you are maybe 70 mph faster) does happen to every driver regardless of how often he/she speeds. It's simply that other drivers often are bad at assessing the speed of an approaching car on the left lane.

The few cars that drive really fast are creating a stressful experience for everyone on the Autobahn.

You can be the world's best fast driver on the German Autobahn with an entire accident-free record, yet you might have caused anxiety and dangerous situations for hundreds of other drivers as "byproduct" of your own driving.

And I am writing that while I do love the Autobahn. I am even a bit shocked that I am now basically ending up arguing for speed limits... :P

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#259

Post by anticensor » Tue, Mar 05, 2019, 8:55 AM UTC

henvic wrote: post #249

jacquesm wrote: post #111

Earlier quoted context omitted.

In all of my 32 years of driving and over many many miles I've had exactly one situation where acceleration helped me avoid an accident and it wasn't anywhere near the local speed limit. On the way to visiting another HN user I was about to turn left and looking into the low sun waiting for a vehicle that was barely visible to pass. Then I moved across the lane and another vehicle appeared quite close behind the prev…

Regarding sudden acceleration (and it's a good time to remember acceleration isn't speed) avoiding accidents... I live in Brazil. There is a tax supposed to cause road accidents here. If your powertrain is > 1.0, the tax you pay when buying cars has a sudden increase. Therefore, many if not most people buy 1.0 cars here (). This is valid even for some that are not consider lower end here (though would be anywhere els…

> If your powertrain is > 1.0, the tax you pay when buying cars has a sudden increase.

What do you mean? Engine displacement>1L? Transmission overdrive? Something else?

Re: Volvo is introducing a 112mph speed limiter to all its new cars

#260

Post by masonic » Tue, Mar 05, 2019, 9:53 AM UTC

PostOnce wrote: post #223

I don't want Volvo, or a computer, or a mechanical system to kill my family because it didn't account for an edge case. Everyone here is talking about normal highway use, but, as everyone knows, not all situations are normal. Bad things happen. My imagination is limited, but for example: Fires can spread quickly and surround you (e.g. a valley with one road out), a tsunami can happen with only a couple of minutes war…

  Fires can spread quickly and surround you

In a wildfire situation, you won't have the forward visibility to drive that fast. You'd rear-end the first car you caught up to.