Dramatic title, I know. But it’s a fair one: TACC with Speed Assist on Model 3 in its current form can be outright dangerous. I’ve seen more people complain about this for more than a year now, but now that I’ve experienced it myself I really feel it should either be fixed or disabled right away for Model 3.
Make no mistake: I love my Model 3 and am extremely impressed with it. It’s simply the best car I’ve ever owned, nothing comes close. TACC with Speed Assist seems to be one of the few major design flaws of the vehicle.
Here’s an example that actually happened to me. It might seem like an edge case, but it isn’t. It’s a very common situation and will be encountered by many drivers on a daily basis.
Tesla Model 3 Performance
Software 2019.32.2.1 9b8d6cd
Expected and safe behaviour
Germany, Autobahn A3, Speed Limit: none
Speed Assist presets TACC to 150 kmh
On TACC engagement, M3 will try to accelerate to and maintain 150 kmh
Unexpected and dangerous behaviour
Germany, Autobahn A3, Speed Limit: none, Temporary Speed Limit: 80 kmh
Speed Assist presets TACC to 150 kmh
On TACC engagement, M3 will try to accelerate to and maintain 150 kmh
Drivers will not expect the sudden and unintended acceleration resulting in possible dangerous situations. Even if drivers are aware, cruise control is effectively rendered useless in these situations.
The main design flaw is that the driver cannot set TACC to the current speed. It will always preset speed to what Speed Assist thinks is the current speed limit (plus/minus offset), this behaviour cannot be overridden. It is impossible for the driver to select current speed, nor is it possible for the driver to overrule the set speed by Speed Assist before TACC is engaged. This would be reasonable behaviour if Speed Assist would recognise the actual speed limit. However, all speed information is currently based on a database. This data is often outdated or incorrect for many roads, does not take into account time of day nor any temporary restrictions.
The only way to operate TACC with SA would be to engage TACC at 150 kmh, but keep the current speed by keeping the accelerator depressed. Only then can the speed be reduced by turning the right scroll wheel. However, reducing the set speed from 150 to 80 kmh takes 14 ‘fast scrolls’. Furthermore, once TACC is disabled and re-enabled, the speed will be set back to 150 kmh, requiring the same procedure again to safely use TACC.
Model S/X does have a very simply way to set the current speed, even with Speed Assist enabled. This is how it should work on Model 3, there is absolutely no reason to have the current design in production vehicles on public roads. It’s a dangerous feature that can result in unexpected behaviour at high speeds.
I have already filed a report with Tesla. This thread is mainly meant to attract as much attention from Tesla and other Model 3 drivers as possible, this needs to be fixed. A fix should be relatively simple: make it possible for the driver to overrule Speed Assist before TACC engagement and/or enable a way to set TACC to the current speed.
Please feel free to share your experiences. Am I missing something? Is there a magic hidden way to overrule Speed Assist with TACC?
TL/DR
SpeedAssist presets speed for TACC based on incorrect speed limits. The driver cannot overrule this prior to TACC engagement, possibly resulting in unexpected acceleration, speeding fines or serious accidents. This behaviour is dangerous and should be fixed as soon as possible.
Make no mistake: I love my Model 3 and am extremely impressed with it. It’s simply the best car I’ve ever owned, nothing comes close. TACC with Speed Assist seems to be one of the few major design flaws of the vehicle.
Here’s an example that actually happened to me. It might seem like an edge case, but it isn’t. It’s a very common situation and will be encountered by many drivers on a daily basis.
Tesla Model 3 Performance
Software 2019.32.2.1 9b8d6cd
Expected and safe behaviour
Germany, Autobahn A3, Speed Limit: none
Speed Assist presets TACC to 150 kmh
On TACC engagement, M3 will try to accelerate to and maintain 150 kmh
Unexpected and dangerous behaviour
Germany, Autobahn A3, Speed Limit: none, Temporary Speed Limit: 80 kmh
Speed Assist presets TACC to 150 kmh
On TACC engagement, M3 will try to accelerate to and maintain 150 kmh
Drivers will not expect the sudden and unintended acceleration resulting in possible dangerous situations. Even if drivers are aware, cruise control is effectively rendered useless in these situations.
The main design flaw is that the driver cannot set TACC to the current speed. It will always preset speed to what Speed Assist thinks is the current speed limit (plus/minus offset), this behaviour cannot be overridden. It is impossible for the driver to select current speed, nor is it possible for the driver to overrule the set speed by Speed Assist before TACC is engaged. This would be reasonable behaviour if Speed Assist would recognise the actual speed limit. However, all speed information is currently based on a database. This data is often outdated or incorrect for many roads, does not take into account time of day nor any temporary restrictions.
The only way to operate TACC with SA would be to engage TACC at 150 kmh, but keep the current speed by keeping the accelerator depressed. Only then can the speed be reduced by turning the right scroll wheel. However, reducing the set speed from 150 to 80 kmh takes 14 ‘fast scrolls’. Furthermore, once TACC is disabled and re-enabled, the speed will be set back to 150 kmh, requiring the same procedure again to safely use TACC.
Model S/X does have a very simply way to set the current speed, even with Speed Assist enabled. This is how it should work on Model 3, there is absolutely no reason to have the current design in production vehicles on public roads. It’s a dangerous feature that can result in unexpected behaviour at high speeds.
I have already filed a report with Tesla. This thread is mainly meant to attract as much attention from Tesla and other Model 3 drivers as possible, this needs to be fixed. A fix should be relatively simple: make it possible for the driver to overrule Speed Assist before TACC engagement and/or enable a way to set TACC to the current speed.
Please feel free to share your experiences. Am I missing something? Is there a magic hidden way to overrule Speed Assist with TACC?
TL/DR
SpeedAssist presets speed for TACC based on incorrect speed limits. The driver cannot overrule this prior to TACC engagement, possibly resulting in unexpected acceleration, speeding fines or serious accidents. This behaviour is dangerous and should be fixed as soon as possible.