Auto-pilot uses more battery than a real driver driving efficiently?

[brianman]

AP much better at conserving energy on the highway. TACC on its own is about the same in traffic. Just my 2 cents.

Huh? How is TACC+autosteer doing anything different with energy use than TACC?

 

[deonb]

Is rapid acceleration less efficient? Yes, it uses more energy but for a shorter period of time to get to speed.

Yes. You roughly need to use 4 times as much power to accelerate twice as fast.

E.g. if you accelerate from 0 to 60 in 8 seconds, you'll draw roughly 75 kW for 8 seconds. If you accelerate from 0 to 60 in 4 seconds, you'll draw 300 kW for 4 seconds - not just 150 kW.

Easily reproducible - go try it out.

 

[jerjozwik]

I think it would be an interesting experiment for you to try setting AP to distance 7 in your daily rat race commute and see what it does to you stress level. (You'll have to get used to people pulling in front of you... just don't let it bother you. I've noticed that people who pull in front usually don't spend much time there; they quickly leave for another "better" lane.)

ha! im stress free with autopilot! the aggro braking comment was in reference to the cars stopping furiosity.

garyjac, all my comments are in reference to being on a motorway, no lights.

 

[marchino]

Yes. You roughly need to use 4 times as much power to accelerate twice as fast.

E.g. if you accelerate from 0 to 60 in 8 seconds, you'll draw roughly 75 kW for 8 seconds. If you accelerate from 0 to 60 in 4 seconds, you'll draw 300 kW for 4 seconds - not just 150 kW.

Easily reproducible - go try it out.

Of course you will use more energy by accelerating more quickly, but after 8 seconds you will have travelled further, so the effect on Wh/km is not as dramatic.

 

[BenT]

When driving on AP and approaching roundabouts, the car stays at programmed speed until it approaches cars slowing for the roundabout then breaks hard. (not much regen). If I deactivate AP knowing a roundabout is looming, then I get regen and brakes are hardly used.

So on AP the Model S uses the brake pads to slow? I would have thought it was all engine braking with regen. I have been using AP or TACC in stop start traffic because I thought it was saving my brakes.

 

[TesAus]

So on AP the Model S uses the brake pads to slow? I would have thought it was all engine braking with regen. I have been using AP or TACC in stop start traffic because I thought it was saving my brakes.

It would still be using full regen, but because it leaves it later than a driver anticipating a slow down it has to brake harder therefore using the friction brakes as well.

As others have noted if you set the sensitivity of TACC up closer to 7 then there is more buffer and it will take it a bit easier. Cars will cut in to the gap, but then the same would occur with an easier manual driving style

 

[EcoCloudIT]

Agreed on putting TACC between 5-7, nicer driving experience and way more green showing. Also found that efficiency is now sorry on par with my manual driving....

 

[jerry33]

Any kind of automated speed / driving controls currently available will always use more energy than a practiced driver because the automated controls currently in existence always brake too hard and accelerate too fast. It should be possible to design a system that is better than a practiced manual driver, but no one has done so yet.