Traffic aware cruise control - initial set speed?

[fcos154]

The Manual states “When driving at your desired speed, set the cruising speed by moving the gear level fully down once then releasing”. But I found that if I am below the speed limit, it usually (but not always) sets to the detected speed limit, not the current (and desired) speed. Once in a while, it does set to the current speed. My local Tesla service could not figure this out, and said they would inquire about it. They didn't have another Model 3 available to compare.

What speed does your Model 3 set to if you turn on cruise control when going below the speed limit?

 

[TT97]

I have mine set at 8 mph over the speed limit. You can change by going to Controls > Autopilot > Settings > Speed Limit Warning and adjust the Relative speed.

I noticed sometimes it does stay at current speed instead of desired speed. Not 100% sure when that occurs. If you are going faster than the relative speed, it will select that speed. Don't know about when it selects a slower speed (it may have to do if it detects a car on front or not).

 

[SDKoala]

The Manual states “When driving at your desired speed, set the cruising speed by moving the gear level fully down once then releasing”. But I found that if I am below the speed limit, it usually (but not always) sets to the detected speed limit, not the current (and desired) speed. Once in a while, it does set to the current speed. My local Tesla service could not figure this out, and said they would inquire about it. They didn't have another Model 3 available to compare.

What speed does your Model 3 set to if you turn on cruise control when going below the speed limit?

Unless someone else can chime in and prove their Model 3 is doing something different, they way you've described it is the way it is designed to work. It can be incredibly dangerous because it can cause sudden unintended acceleration

The problem occurs because the car takes speed limit data from the built-in map. When you engage TACC below the stored speed limit, EAP will set your speed at the limit stored in the map. It will do this regardless of the actual real life speed limit. There are a lot of speed limit mistakes in the map so it happens quite often. For example, my residential street has a 25 MPH limit, but on the map it's stored as a 55 MPH limit. If I engage TACC right outside my driveway, it will launch toward 55 MPH unless I can quickly turn the scroll wheel to dial down the max speed.

If there is no stored speed limit data in the map, the car will set TACC at your current speed. This is the way it should be and the way every other car cruise control works, but Tesla has complicated things by tying TACC to the speed limit data in the map. It probably has to do with being able to engage Autosteer safely, so you can't force it to Autosteer at 70 MPH in a 35 MPH zone where it might not be physically possible.

I've reported this to Tesla and others should too so they know it's a problem. I have no idea if TACC in the Model S or X works the same way.

 

[fcos154]

SDKoala, If this is the way TACC is designed to work, why does the manual (on page 61 of the pdf manual) say “when driving at your desired speed.....” (see my post above for full quotation). This implies to me that it should set at current speed.

 

[bpjod]

SDKoala, If this is the way TACC is designed to work, why does the manual (on page 61 of the pdf manual) say “when driving at your desired speed.....” (see my post above for full quotation). This implies to me that it should set at current speed.

That's because they presume your "desired speed" is above the posted speed limit

Mine works the same way. I have set mine to Relative & +7 kph over the posted speed limit. If I'm above that and I set it, it will set my speed to whatever I'm driving at as per the manual. If I'm below the speed limit, it will set it to the posted speed limit + 7kph.

A few observations about this:

• What they think the posted speed limit is, and what it actually is are sometimes 2 different things.
• The way it works is awesome in stop/go traffic. Once the congestion eases, you'll accelerate to the speed limit + offset and stop there. I rented a Model 3 in Chicago for 4 days and drove the I-90 to downtown and back out on 3 of those days. I came to really love this feature.
• I wish the relative offset could be a percentage rather than a fixed amount over the posted speed. I'd like +10% as 10 kph over in town feels a bit excessive whereas it feels about right on the highway. I've compromised with +7 kph, then fine tune with the scroll wheel after engaging, but I'd rather have it offset by a %age.
• It would be nice if there were a way of reporting the incorrect speed limits in their database.

 

[SDKoala]

SDKoala, If this is the way TACC is designed to work, why does the manual (on page 61 of the pdf manual) say “when driving at your desired speed.....” (see my post above for full quotation). This implies to me that it should set at current speed.

Because the person who wrote the manual is probably had nothing to do with designing TACC behavior? Or it's a bug that's been overlooked and we should all be reporting it before someone collides into something by accident? This is a potential cause of sudden unintended acceleration that would not be due to a panicky driver stomping on the accelerator thinking it was the brake.

The bottom line is the car should always set cruise control to the current speed. I'd like to see an argument why setting it to the speed limit is better, especially with all the speed limit errors in the maps. I'm really surprised this doesn't bother more people. It's up there in the top 5 annoying things about the car for sure.

 

[Gyanofcary]

The Manual states “When driving at your desired speed, set the cruising speed by moving the gear level fully down once then releasing”. But I found that if I am below the speed limit, it usually (but not always) sets to the detected speed limit, not the current (and desired) speed. Once in a while, it does set to the current speed. My local Tesla service could not figure this out, and said they would inquire about it. They didn't have another Model 3 available to compare.

What speed does your Model 3 set to if you turn on cruise control when going below the speed limit?

Posted speed limit.

 

[flashflooder]

That's because they presume your "desired speed" is above the posted speed limit

Mine works the same way. I have set mine to Relative & +7 kph over the posted speed limit. If I'm above that and I set it, it will set my speed to whatever I'm driving at as per the manual. If I'm below the speed limit, it will set it to the posted speed limit + 7kph.

A few observations about this:

• What they think the posted speed limit is, and what it actually is are sometimes 2 different things.
• The way it works is awesome in stop/go traffic. Once the congestion eases, you'll accelerate to the speed limit + offset and stop there. I rented a Model 3 in Chicago for 4 days and drove the I-90 to downtown and back out on 3 of those days. I came to really love this feature.
• I wish the relative offset could be a percentage rather than a fixed amount over the posted speed. I'd like +10% as 10 kph over in town feels a bit excessive whereas it feels about right on the highway. I've compromised with +7 kph, then fine tune with the scroll wheel after engaging, but I'd rather have it offset by a %age.
• It would be nice if there were a way of reporting the incorrect speed limits in their database.

This is a brilliant idea that they should implement ASAP.

 

[Gyanofcary]

This is a brilliant idea that they should implement ASAP.

+1

 

[mpt]

@SDKoala is correct IMO.

In Short: I think this is an issue and one that may wind up on the front of the next 'Let's short Tesla' headline. It is a Model 3 only problem, S/X & Roadster don't suffer this issue.

At length, I've been nagging Tesla since the first time I activated cruise control at 25mph in a school zone and was suddenly launched forwards by the car! It won't hit anything, as it's distance aware so, this isn't a big safety concern but, for me, I'm finding that I can't use cruise control very much at all and I want a refund.

I've spoken to Tesla and been surprisingly misunderstood. It seems that the whole interface is misleading as they seem to have inadvertently co-mingled speed warning and cruise control onto the same set of UI controls:

• Speed warning is a feature to help avoid unintended speeding, basically, to avoid a ticket.
• Cruise control is a feature to maintain vehicle speed automatically.

These are not connected however, in Tesla parlance they seem to have inadvertently become one. I think that everyone at Tesla is misunderstanding my complaint/fear* because of this connection.

One proposal I received from Tesla was a solution where the speed warning buffer would be updated to allow a negative value.

Below I’ve laid out the concern, and a simple fix. I’ve also outlined why the current proposed fix will not work.

Example failure scenario

1. My local school is on a 40mph road. During school hours the speed is 25mph whilst lights are flashing. There is a long downhill followed by a long uphill. I can’t use cruse control in this scenario as the car accelerates to 40mph regardless of the time of day.
2. Traveling on the NJ Parkway I hit long stretches of roadworks with speed limit of 45mph. I can’t use cruse control at this time as the car accelerates to the assumed limit of 65mph.
3. I want to have speed warning set at 5mph above the posted signs. If I do this, I can’t use cruise control at the posted limit, instead that car accelerates to the posted limit PLUS the speed warning margin.
4. I’m driving on a 35mph road at 35mph however, the car is mis-categorizing the post speed limit as 45mph. I cannot use the cruise control as the car accelerates to 10mph over the posted limit (more if the extra 5mph buffer were included!) (please don’t ask where this occurs, fixing the GPS database is not the issue at hand here

The simple ask

I can’t set my cruise control to the current road speed because the car instead, accelerates violently to what it believes is the maximum posted speed I should be driving at.

This is clearly wrong, if you read what I’m saying, the absurdity should become clear.

The simple fix

1. Enable the ‘set’ function on the cruise control to set at the current road speed.

Why the current proposed fix won’t work
The proposed fix of allowing a ‘negative’ speed warning offset will result in the speed warning chime sounding every time you cross the threshold. For example:

1. I set the offset to -5mph. The warning chimes every time I hit 35mph on a road with a posted speed limit of 40mph.
2. I set the offset to -5mph. When driving in a school zone on a road that has a 40mph posted limit, setting the cruise control results in the car accelerating to 35mph.
3. I set the offset to -20mph to ensure I can set the speed to 25mph in a 40mph zone. The warning chimes nearly every time I get out of my driveway.

If anyone has any ideas on how we can get this fixed, I'm all ears!


**My fear is that this phenomenon will be branded as ‘unintended acceleration’ which always has the media in a fizz. Now is not the time for more crazy press! I’ve managed enough ‘situations’ with Tesla during the early years running Tesla Motors Club, when I’d get a call from Rachel Konrad or even Colette Niazmand because of some stupid comment (Now known as 'fake news') about a Tesla fire or some accident that proved electric cars where dangerous, so I know how quickly mis-information can be twisted and this feels like just that kind of thing.

 

[SDKoala]

The simple fix

1. Enable the ‘set’ function on the cruise control to set at the current road speed.

This is all that is needed and the problem is fixed. Want a different speed? Scroll up/down to set, or drive to that speed first, then set cruise control. Pretty much the way every car's cruise control system works.

Like I wrote earlier, I'm sure the reason we would get from Tesla why it can be like this has something to do with safe driving speeds for Autosteer.

 

[mpt]

This is all that is needed and the problem is fixed.

That would do it for me but there are others that probably want 'jump to posted speed' and I think that could be accommodated. There's a detent in the control so how about:

1. Press down lightly to set at road speed.
2. Press down firmly to set at posted limit.

 

[SDKoala]

That would do it for me but there are others that probably want 'jump to posted speed' and I think that could be accommodated. There's a detent in the control so how about:

1. Press down lightly to set at road speed.
2. Press down firmly to set at posted limit.

Perhaps, but there are things that we aren't able to do for safety reasons and jumping to stored map speed (since there car isn't reading actual posted speed) should probably fall in that category. It still leaves the possibility of unintended acceleration by a mistaken press of the stalk.

 

[mpt]

...there are things that we aren't able to do for safety reasons...

I agree somewhat, normally, I'd say that a car shouldn't accelerate when you engage cruise control however, there's some precedent for this, 'resume' on a regular cruise control and, S/X cruise control does, depending upon how you engage it, either set at road speed or set at guesstimated posted speed. With Tesla already pushing the auto envelope, I'd say keep it, it's interface is similar to the indicator stalk action so safely familiar.

For me, the option of switching it off altogether, including TACC distance sensing, would be bliss - no more jarring, random slow down/speed up because it thinks it's seen a squirrel! I had an i3 which had the equivalent of AP 0.5 from MobileEye, it was too unreliable and had an option where if you press-hold the distance set button it would cut off and revert to old-school cruse control where I could set it at whatever speed I wished - bliss.

 

[SDKoala]

I encourage people to report this to Tesla through the website. With how much bad press AP has gotten lately, being able to identify and correct something like this would be a big step toward making the cars safer. The diagnostics team pulled the data from my car and they are supposed to have more information for me next week.

 

[favo]

Doesn't the 3 show you what it thinks is the speed limit with a facsimile speed limit sign on the display? I also thought that tapping that facsimile sign would set cruise to that speed. They could leave that functionality as is, and change the stalk to set cruise to current speed. That would force you to look at what the car thinks is the speed limit, and should reduce surprises.

 

[daniel]

What I'd like to see is allowing the scroll wheel to adjust the set speed before engaging TACC. If I'm on a 25 mph road but the car thinks the limit is 35, I want to be able to change it. In fact, turning the scroll wheel when TACC is not engaged does nothing. I'd have to engage TACC and immediately and quickly spin the scroll wheel down.

I'm not confident that this would prevent speeding, so I don't use TACC on those roads.

Most of the time I like the way it works. As long as the car knows the correct speed limit (which is most of the time) I start driving and then engage TACC and it speeds up to the set speed. This is normally the behavior I want. Now if they let me lower the set speed below what the car thinks the limit is before engaging TACC, it would be perfect.

There's also a real opportunity to correct the map data: Monitor when people lower set speed before engaging TACC, and if enough people do this on a given road, change the map data, or have someone check the map data against local municipal records.

 

[mpt]

so I don't use TACC on those roads

Which is why I'm personally frustrated by all of this - it was an expensive option and can't use it very often :-(

I'm in a dialog with Tesla regarding my complaint, as is SDKoala I gather; write your representative (at Tesla), this is just software and we'll get this fixed for generations to come... OK perhaps that was a bit strong.

 

[CqEv3]

Bpjod idea of a %delta instead absolute us is a rather good one I like. But in USA most places the traffic violation is when the speed exceeds about 10 mph above the limit. So many people drive 6-9 miles above.

Btw, tacc already auto reduces the distance from the front car if the speed is lower than highway speeds.

 

[GSP]

That would do it for me but there are others that probably want 'jump to posted speed' and I think that could be accommodated. There's a detent in the control so how about:

1. Press down lightly to set at road speed.
2. Press down firmly to set at posted limit.

I also find it frustrating not to be able to set cruise control at the current vehicle speed. All other cars ever made with cruise control can do this, including Roadster, S, and X. I sure hope Tesla offers a software fix soon.

I like the above suggestion, as it allows either vehicle speed, or the speed limit warning speed to be selected. The S and X offer this, and I use both options in my S.

Another way to achieve this would be:

1) press down lightly once to engage TACC at the present vehicle speed
1a) after step 1, press down lightly twice to engage auto steer at the current TACC set speed (which may have been adjusted by the driver after step 1)

2) press down lightly twice to engage both TTAC and auto steer at the speed limit warning speed

I don't care which option, or if another method is chosen. I just want to be able to set cruise at current vehicle speed.

Tesla employees: Please put this as a high priority software feature for the 3, and thank you for the wonderful cars you make and all the hard work that you do.

GSP