Acceleration discontinuity when transitioning through 0 velocity.

Acceleration discontinuity when transitioning through 0 velocity.

I live in a hilly area (Santa Cruz mountains), and have been driving my new 60kWhr model S for a couple of weeks. I've noticed that if I have the selector in D, and push the accelerator when the car is rolling backwards, I get a glitch in the acceleration. It feels like the car first decelerates from negative velocity to 0, pauses for a split second, then starts accelerating forward. Has anyone else noticed this glitch?

sergiyz | February 11, 2013

Yep, same here, and same if you're in reverse and rolling forward.
I've started seeing it with 4.1 and above.
I can't say it's a bug, just a different response.
I like throttle response in 4.1 and above much better overall than in the prev versions.

EcLectric | February 11, 2013

My experience is a sudden surge in acceleration when starting from an uphill stop. Same thing - happens when I roll back a little.

mal42north | February 11, 2013

I did not have 4.1 installed for long enough to see this issue. Maybe its something else that will get fixed in 4.3 :-). I think its a bit of a tradition with Linux, to stick to the odd revisions.

July10Models | February 11, 2013

Do you have creep set to off for on? In my car creep mode is off because I like rocking the car back and forth when stop on hills. I know this burns more juice but it is a hobbit of mine. I haven't noticed this in my car even though my commute takes me through some congested areas. I'll have to try this on steeper hills

kevjo | February 11, 2013

My 60kw is parked in our driveway (pointing up hill) on a slope that's probably 3-5%. I have creep turned on but still the car rolls back slightly before moving forward. I've never experienced the effect that others describe.

Brian H | February 11, 2013

Watch out for bad hobbits. They can be deadly.

July10Models | February 11, 2013

I do this all the time when I drive a manual transmission car. The big rear view display makes it easy to avoid hitting things that sneak up behind the car. A few years ago while sitting behind a tractor trailer at a stop sign at the top of a hill it saved the front of my car from getting dent because the truck backed up about three car lengths before getting the truck under control. All I did was sink my clutch and slid back to give him room. It would have been a different story with another vehicle behind me though.

Brian H | February 11, 2013

It's all explained by the Theory of General Relativity, and frames, but it's too complicated to go into here. );/

mal42north | February 12, 2013

I have creep turned off on my car. I do notice that if I stop the car from rolling backwards using the accelerator, I do not notice the glitch.

July10Models | February 12, 2013

@Brian H - habit!

davy_as | February 13, 2013

I love tesla very much, i like reading and watching elon musk and tesla model S on youtube.
I have question regarding on hilly road but i dont know where i can write it so tesla will read and answer my questions. i hope my questions will help tesla improving their car ;)

I have question regarding on hilly road. it reminds me to the indonesian tucuxi first testing electric car. the same as tesla, tucuxi doesn't have gearbox. my question are
1. is it true when we drive down on hilly road declining about 45 upto 60 degrees and speed 60 upto 100 kmph, the brakes hard to reduce the acceleration as gravity increases the speed? i do understand the powertrain will reduce acceleration as it doesnt get electricity when we push the brakes, but powertrain will not stop the speed and brakes will hard to handle it.

2. Please consider the hilly roads in San Fransisco, they park tight on that hilly roads, it will cause an accident when the glitch happens ;)


July10Models | February 13, 2013

regen doesn't stop when you apply the brakes. regen continues as long as the wheels are still turning. When the brakes are applied they just provide additional stopping power. When you drive this car, it is more like being plugged into it. You know that scarry feeling when brake lights are filling your view really fast, totally absent in the Model S because as you take your foot of the gas pedal the regen kicks in a very organic manner to let you know that everything is ok even before your foot reach the break pedal. When the brakes are applied the car respond solidly to halt without any complaints.

Brian H | February 13, 2013

There are no hills in the world you can drive at 45-60°. Very few over 10°. A hill that steep would send you down sliding on your face.

davy_as | February 13, 2013

@July10Models and @Brian H

Thank you for your reply :)
please correct me :)
yes i agree, i think the hilly is declining less than 30 degree :)

so, the powertrain and regen will help and give additional power brake?
what I am wondering is the dynamo of regen and powertrain will keep rotating while speeding on downward hills and breaks will take it all.

Electric car with regen is my dream since i was in Junior high.
Can Tesla make an additional power regen in front trunk as in below youtube? So, it will regen when we park it while we are working in the office :)

My dream of an electric car is an independent / self regen power and now my dream is to meet Mr. Elon Musk who makes my dreams become reality.


jbunn | February 13, 2013

It always regens downhill if you are not trying to accelerate. There is no regen in park, or self regen, as this would be a kind of "perpetual motion" device. These are not allowed by physics.

Timo | February 13, 2013

It always regens downhill if you are not trying to accelerate.

Not quite. Air drag and rolling resistance at higher speeds slow you down more than hill accelerates if the hill is not steep. At 60mph it takes approx 20kW just to keep car moving, so it starts to regen only after you go pass that threshold. You do use less energy of course going downhill than you would going flat plane all other things being equal.

davy_as | February 14, 2013

@jbunn and @Timo
please correct me :)

my idea is, the self regen will start when the car engine is off.
yes agree, it is not allow by physics.
Perpetual motion describes "motion that continues indefinitely without any external source of energy; impossible in practice because of friction.
but wait a moment, external source of energy is the magnetic field and the magnetic field will not reduce its power. yess agree friction will reduce the motion but the magnetic field will keep emitting the power and the magnetic field itself is an isolated system :)

it depends on how many micro tesla will cover the friction to keep it rotating :)


Timo | February 14, 2013

Magnetic field is not isolated system. nuff said.

Brian H | February 14, 2013

No, not even 30°. Get a level and protractor and start checking hills. You won't get anywhere near that number on a road cars can use. Goats and strong people, maybe.

Timo | February 14, 2013

I once drove up a hill that was over 45° steep (at it's steepest point guy at the back measured 58°). No road, just a hill. It was crazy, your weight is at your back, not at your legs, car floor was more like a wall and back wall was floor. No ordinary civilian car could get up that steep hill, you lose traction. Or power. Or both.

Brian H | February 14, 2013

Yeah, they call it "off-roading" for a reason. You learn where your CoG is in a hurry.

davy_as | February 15, 2013

Thank you guys for the answers and reply :)
I am so happy and keep updating to this forum.

Please update me when Tesla launch Model S in Indonesia :)
I am waiting for that moment.

@Timo and @Brian H @July10Models @Jbunn
I am so curious with the magnetic regenerator, i know this is out of this forum topic.
if u guys dont mind, i wanna discuss and learn more about it by email. my email is

once again thank you guys and thank you Tesla :)