How do you launch your car (non-P versions)

[TwitchADC]

Quick newbie question...

I noticed with Ludacris mode enabled cars, there is a dedicated launch more (step on brake with left foot + gas right foot, etc).

Is there an equivalent way of doing this for a 75 or 75D? If not, whats the best way to test the car from dead stop to 60 (aside from stomping on the gas from stop).

 

[Derek Kessler]

1. Bring the car to a stop.
2. Press through the brake to activate brake hold. A (H) icon will appear on the dash. You can lift your foot off the brake.
3. Ensure that you have a clear path ahead.
4. Mash the accelerator.

i.e. There's no launch mode on non-Performance cars — just pedal to the metal.

 

[Haxster]

Press through the brake to activate brake hold.

Seems like this might put undo stress on the brake assembly when doing a pedal to the metal launch. Yes? No?

 

[SoAmpt]

Derek Kessler

Seems like this might put undo stress on the brake assembly when doing a pedal to the metal launch. Yes? No?

Possibly, but Derek's instructions are identical to those given to me on my test drive.

 

[Haxster]

Another data point:
When the car is pointed down a hill with brake-hold on, the instructions are to push the brake pedal to release the brake before pressing on the go pedal. You don't have to, but the reason they instruct you to do so may have to do with stress on the brake release mechanism...the same one used to disengage the brake when flooring it from a stop on level ground.

As Leonard Bernstein wrote in West Side Story, "Could be. Who knows..."

 

[mal_tsla]

I imagined the car would simply release the brake before delivering power, thereby avoiding any extra stress. Seeing as the Vehicle Hold is a software feature and the accelerator is fully electronic, it would be trivial to sync that up perfectly in software to launch the car a split second after you mash the pedal. If the car doesn't bother doing this, my guess is because the extra wear is no big deal.

In any case, a quick tap of the brake pedal to release the Hold should provide for a slightly more dramatic launch since the friction brakes are removed from the equation entirely

 

[Ande]

All cars have a secret mode with Ludicrous and lauch, you just need to unlock them by a code: (very much like a nintendo)
-Take 4 left turns
-take 5 right turns
-brake 2 times
-honk the horn
-open all the doors, then close them
-run around the car three times.

 

[Derek Kessler]

Seems like this might put undo stress on the brake assembly when doing a pedal to the metal launch. Yes? No?

Nah. It's an electronic release — the brake releases the instant you press the accelerator. While the acceleration is brisk, the brakes are lifted before the wheels start spinning. I use brake hold + accelerate all the time at stop lights (well, usually without mashing the pedal) to no ill effect.

 

[Leopold Stotch]

Read something before about Tesla restricts the amount of “full stop launches” on P vehicles. So would take it easy on launches with non P as well. I treat my Tesla like a baby.

 

[eschummer]

↑ This. Also helps your lifetime average kWh/mile....

 

[mal_tsla]

Does it necessarily help your lifetime average kWh/mile?

One of the things I love about the Tesla is you can start briskly and then recover most (all?) of that energy, whereas in my gas car it is hard to avoid getting on the friction brakes after a quick acceleration. For example, accelerating for 2 seconds at 150kW and then coasting on regen a few seconds up to that next turn at the intersection should net kWh consumption similar to an "eco start", but leaves a nice smile on your face nonetheless.

 

[Derek Kessler]

Does it necessarily help your lifetime average kWh/mile?

One of the things I love about the Tesla is you can start briskly and then recover most (all?) of that energy, whereas in my gas car it is hard to avoid getting on the friction brakes after a quick acceleration. For example, accelerating for 2 seconds at 150kW and then coasting on regen a few seconds up to that next turn at the intersection should net kWh consumption similar to an "eco start", but leaves a nice smile on your face nonetheless.

You'll only recover part of the energy. Thanks to the law of conservation of energy (the physics law, not any governmental regulation), regenerative braking will never be able to recover all of the energy spent. You're fighting air resistance, friction, gravity, heat loss, and more.

It is more fun, however, and the total kWh usage isn't going to be absurdly affected for the average driver.

 

[BrettS]

One of the things I love about the Tesla is you can start briskly and then recover most (all?) of that energy

You can definitely recover some energy with the regenerative brakes, but as the pp said, it is just a small fraction. I had a Prius before my Tesla and some folks on one of the Prius message boards did some tests a number of years ago and determined that using regen to decelerate from X to 0 recovered about 1/3 of the energy necessary to go from 0 back to X.

It’s certainly better than not recovering any energy, but you’re fooling yourself it you’re thinking that you’re getting most of it back.

 

[mal_tsla]

I must sound like a dummy or something.

Can we agree that 2 seconds of accelerating at 150kW can be replenished 50% by three seconds of regen at 50kW as indicated on the dash meter?

Thus those two seconds of fun "cost" the same as boring acceleration at 75kW?

 

[BrettS]

Thus those two seconds of fun "cost" the same as boring acceleration at 75kW?

This is assuming that it will use the amount of energy to accelerate to X MPH at 150kW as it will to accelerate to the same speed at 75kW and that’s simply not the case.

There are a lot of factors at play here, but there is a lot of discussion on this here...

Why does accelerating fast use more energy than accelerating slowly?

 

[Mediocrates]

Can we agree that 2 seconds of accelerating at 150kW can be replenished 50% by three seconds of regen at 50kW as indicated on the dash meter?

This math is correct. However, the situation is artificial. You won't be able to achieve the scenario you described.

 

[mal_tsla]

This is assuming that it will use the amount of energy to accelerate to X MPH at 150kW as it will to accelerate to the same speed at 75kW and that’s simply not the case.

There are a lot of factors at play here, but there is a lot of discussion on this here...

Why does accelerating fast use more energy than accelerating slowly?

Yes, I know. I never said I would accelerate to the same ending speed in both cases.

One is likely a quick sprint to nearly 60mph, and the other is likely a leasurely swell to maybe 40mph.

My point is: the car has an energy flow indicator on the dash. It doesn't lie. If your rapid acceleration is followed by heavy Regen, you can do math to figure your net consumption and it's not simply "launching hard causes high lifetime average kWh" as stated above.

 

[mal_tsla]

This math is correct. However, the situation is artificial. You won't be able to achieve the scenario you described.

I'll bite. Why not?

 

[BrettS]

Yes, I know. I never said I would accelerate to the same ending speed in both cases.

One is likely a quick sprint to nearly 60mph, and the other is likely a leasurely swell to maybe 40mph.

My point is: the car has an energy flow indicator on the dash. It doesn't lie. If your rapid acceleration is followed by heavy Regen, you can do math to figure your net consumption and it's not simply "launching hard causes high lifetime average kWh" as stated above.

Not accelerating to the same speed is going go skew the numbers by even more. Using the numbers you posted above, say you launch hard to 60mph at 150kW for 2 seconds and regen for 3 seconds at 50kW for a net energy usage of 150kW. On the other hand, say you “leisurely swell” to 40mph at 75kW for 2 seconds and regen at 25kW for 3 seconds, for a net energy usage of 75kW. You have consumed twice as much energy for the launch.

Instead of making up numbers and assumptions, you can see this for yourself with the car’s energy meter that doesn’t lie. Drive to somewhere you can make a few hard launches, then go to Controls, then Trips and reset one of the trip odometers. Do a few hard launches to 60mph and regen stops, then see what the Wh/mi reading is on the trip odometer. Then go back to your starting position, reset the trip odometer and do a few leisurely swells up to 40mph and regen stops and see what that Wh/mi reading is. I suspect you’ll be surprised by the difference. You could do a third test and do your leasurely swells up to 60mph to compare apples to apples a little better, but even doing that you will have a significantly lower average than you did with the hard launches.

Now obviously doing an occasional hard launch to have fun or show off the car isn’t going to make a significant impact in the lifetime average over 30,000 or 60,000 miles, but if you do hard launches every day it will absolutely raise that lifetime average. In the end though, does it really matter? Drive the car the way you want to. It’s silly to chase numbers and not have fun just because you want to see a low average consumption.

 

[mal_tsla]

BrettS, I think with different sets of assumptions, we can all be right. True?

For example, I don't think I'll need 3 seconds of regen slowing if I'm only doing 40 when it's time to stop, whereas from a higher speed I have more momentum to shed in time for that next turn. And obviously, if the initial speed is zero, that's different than hard acceleration from a roll, etc. Then there's the distance to the point of slowing, and the deceleration curve used.

I love the idea of using the Trips / Reset to play around with this in practice, though. I hadn't thought of that. I won't waste any more time here debating whether or not the scenarios (I've obviously inadequately specified) work out or not, I'll just go play Thanks!

Totally agree about driving the car like you want to and not worrying about the lifetime average. This is all about my nerd curiosity. I'm not clear why average lifetime Wh/Mi would _really_ matter beyond that.