Adaptive cruise control

[Hootgibson]

We picked up our car three hours ago and were shocked to find that it has adaptive cruise control. I wasn't even aware that this was a part of the package. Our delivery specialist didn't know how it works. He told us to read the manual. Has anyone used it?

 

[ArtInCT]

I do not know how the Tesla systems works however, we have Adaptive Cruise Control in our 2011 1/2 Volvo XC60 (also with Blind Spot Information System and City Safe systems). To use ACC in our Volvo you just set your speed as with any other typical cruise control. A sensor in the Volvo's Front Window "sees" the car ahead of you and if that car begins to slow down so will the Volvo and it with attempt to maintain the distance between vehicles. Then, if the car ahead speeds up so will the Volvo until the SET speed you set the Cruise Control to is attained. It is a good system and when it is working correctly you are not really much aware of it. Is it flawless? No. It can loose contact with a car in front of you, on say a sharp bend and speed up. But there are not too many sharp bends on interstates but this did happen in PA once. Also, if the car ahead pulls away by speeding up well beyond your SET speed the ACC will deactivate as it can no longer "See" the target auto.

Ford now has access to that technology (Fusion and possibly others) as they once owned Volvo.... and I suspect other car companies have it now as well.

I feel the blind spot warning system known as BLIS (in Volvo parlance) is a much more important feature. It warns you via a little light (near each side mirror) near the side view mirrors, that someone has pulled up into your rear quarter blind spot (left or right). Really a nice safety feature. These can also get confused in very heavy rain when water pools up on the side view cameras which are located just under the side view mirrors. This has happened once or twice.

Art

 

[ecarfan]

We picked up our car three hours ago and were shocked to find that it has adaptive cruise control. I wasn't even aware that this was a part of the package. Our delivery specialist didn't know how it works. He told us to read the manual. Has anyone used it?

It has been posted that the new steering wheel stalks now show "ACC" on the end of the Cruise a Control stalk but pressing that button does not result in anything new happening.

So when you say your new S "has adaptive cruise control" do you mean that it has a working ACC feature that you have used on the road? I suspect not. Don't assume that just because the stalk says ACC on it that it offers that feature. I believe that feature is coming in the future but it's not working yet. It will be a software change later.

 

[Vitaman]

I agree with Art.
My last 3 cars have all had ACC.
I think I have used it twice. Once to see how it worked. The other to show off the technology to passengers.
I am sure there are some that would use it daily, but it would have been last on my list of new features wanted.

 

[felixtb]

I agree with Art.
My last 3 cars have all had ACC.
I think I have used it twice. Once to see how it worked. The other to show off the technology to passengers.
I am sure there are some that would use it daily, but it would have been last on my list of new features wanted.

Its actually a very nice feature on long and boring drives on the highway. like taking your car on the family vacation. It relaxes the drive a lot and you get less tired. I love to drive but sitting for hours on end on a highway run is both boring and tiring. This is where the ACC comes in perfectly

just my two cents

 

[Doug_G]

Does ACC use brakes? On most cars it can only decelerate... on Model S it might be able to use regen as well but that would not be significant enough to brake strongly.

My former Infiniti G37 could brake up to 50% force. In fact the system would try to avoid a crash even if it wasn't switched on (never tried that feature...)

We picked up our car three hours ago and were shocked to find that it has adaptive cruise control. I wasn't even aware that this was a part of the package. Our delivery specialist didn't even know how it works. He told us to read the manual.

Seriously??? I've been wanting that feature for two years! I wonder if it's available as a retrofit?

I agree with Art.
My last 3 cars have all had ACC.
I think I have used it twice. Once to see how it worked. The other to show off the technology to passengers.
I am sure there are some that would use it daily, but it would have been last on my list of new features wanted.

It's pretty easy to accidentally exceed your intended speed in the Model S, because it is so smooth and quiet and so powerful. I'd use it all the time.

 

[mymacbook]

My wife and I just got home from the factory (9/28 - 2pm) and we walked through all of the tents and every single Model S being delivered had the proper hardware visible for Adaptive Cruise Control / Driver's Lane Assist / Speed Assist. Very exciting times!

 

[Hootgibson]

After digging a little further it seems that our delivery specialist was mistaken. What he was referring to is Lane Assist and Speed Assist. The manual refers to a camera mounted on the windshield behind the interior rear view mirror. I also noticed that it has a much higher resolution driver display than the loaner I drove last week.

 

[dsm363]

If this feature comes out I doubt you can retrofit it since you can retrofit the driver assistance package.

 

[RDoc]

Because using ACC doesn't change braking distance, and your question is a perfect example of how people are going to stupidly rely on this feature thinking that it is a substitute for having common sense and a basic understanding of physics. If you are drafting a big rig and that big rig slams on his brakes because of something up ahead, you think ACC is going to miraculously save your butt when you are following less than a car length behind? You don't need ACC in this instance, as the big rig itself will prove to be a sufficient stopping force for your vehicle. Unfortunately, by the time your S comes to a complete stop, you and all of the occupants in your vehicle will likely be dead.

But hey, you saved 10 Wh/mi.

As a matter of fact, yes I do think the ACC will save my butt, but not through magic. The ACC is capable of reacting in a few milliseconds and the Tesla will stop far faster than a semi. If you actually have a "basic understanding of physics" try working the math.

 

[WarpedOne]

If you actually have a "basic understanding of physics" try working the math.

That is completely unreasonable expectation of people who in general don't have a clue about anything, let alone math or even physics.
Just let it be.

 

[AmpedRealtor]

As a matter of fact, yes I do think the ACC will save my butt, but not through magic. The ACC is capable of reacting in a few milliseconds and the Tesla will stop far faster than a semi. If you actually have a "basic understanding of physics" try working the math.

Everything you say may be true, or not, but still would depend on technology to save your life. That's never a good position to put yourself in, is it? Sensors fail and computers crash. That's not a choice I would make, but congratulations.

 

[ThosEM]

I've never used ACC, but IMHO, it should be illegal to follow closer than 1 car length per 10 mph of control speed, and impossible to do it using an ACC. Whenever I encounter anyone tailgating me at a consistent 1-4 car lengths on the highway, ACC or not, I activate my four way flasher and slow until the definition of tailgating is no longer met, if they haven't passed me by then.

 

[AmpedRealtor]

+1 ThosEm!

 

[riegetor]

Everything you say may be true, or not, but still would depend on technology to save your life. That's never a good position to put yourself in, is it? Sensors fail and computers crash. That's not a choice I would make, but congratulations.

It's not the ACC's job to stop your car for you, it's the brake assist. Yes, it most likely uses the same sensor, but brake assist and adaptive cruise control are two different functionalities and the former do not depend on ACC being active.

Then again, it's not a matter of depending on this saving your life. This is functionality that triggers and automatically brakes in those cases where you are too late. Even when your car has brake assist, you should drive as you normally do. Brake assist is never triggered if you drive as you are supposed to do.

 

[RDoc]

Well, this is going to be my last post on the subject unless someone else does some math, but a few points;

• If you don't want to rely on technology to stay alive, don't fly, use trains, elevators, etc.
• One car length per 10 mph is seriously dangerous for manual control. At 60 mph, 6 car lengths is about 100 ft which is about 1.25 seconds of spacing which is far to close since most people take about 1 second to react and start braking. Almost all your spacing will be gone before you even start to stop and the car in front of you will now be moving much slower than you. Moreover, stopping distance goes up with the square of the velocity. It's far safer to keep a constant time distance between cars, typically 2.5 - 4 seconds depending on traffic since time is linear with velocity and you have a constant reaction time cushion.

This is a chart of what would happen at about 65 mph (30 m/s) following a truck at 5m if it slammed on its brakes. Trucks take about 350' to stop from 60 mph (longer if unloaded), about .35g. Teslas take 108', about 1.1g. I'm assuming the car doesn't do anything until the distance has closed to 4.5m and doesn't apply the brakes full on till it's closed to 4m and it takes .4 sec for the brake pressure to fully build up after first application.

The green distance curve is in meters, the red and blue car and truck acceleration curves are in m/sec/sec. The X axis is seconds.
The closest distance is just under 3 meters, the Tesla stops after 63.7m at 3.7 sec, the truck after 132.8m at 8.9 sec.

 

[TesAus]

Everything you say may be true, or not, but still would depend on technology to save your life. That's never a good position to put yourself in, is it? Sensors fail and computers crash. That's not a choice I would make, but congratulations.

Just for comparison sake do you feel comfortable riding on many transit systems at airports and in major cities - a lot of those are driven solely by computer?

 

[SCDrJ]

ACC should be used to prevent an accident when driving in safe conditions, not as a means to follow more closely to save a few MPG or Wh/mi in my opinion. This type of tech would seem to lead to semi-autonomous driving at some point, but I don't think that's ready for prime time.

 

[David_Cary]

Following "too close" could easily lead to 20% energy savings. A huge benefit of autonomous driving.

Source - Mythbusters, 55 mph, 50 ft back, Lead vehicle - big rig.

Of course 10 ft back was a 40% energy savings.

10 wh/mi? - a bit more than that....

 

[eepic]

Following "too close" could easily lead to 20% energy savings. A huge benefit of autonomous driving.

Source - Mythbusters, 55 mph, 50 ft back, Lead vehicle - big rig.

Of course 10 ft back was a 40% energy savings.

10 wh/mi? - a bit more than that....

The figure would vary quite a bit depending on vehicle gross weight, current wind conditions, air density, etc.

All drafting does is improve aerodynamic drag and given the slippery profile of the heavy Model S, probably the benefit would be much lower than most other cars.