Fail safe is only for nitro and gas. With electric if signal is lost the car will stop.

Not always. I've seen plenty of runaway electric cars.

But still, if you can not switch it off you have to be sure it is configured in the right way.

You don't use fail safe fore electric. It has to be turned on to be used. I have see what happens when you when it's turned on for electric. BYE BYE! It's 1000% useless if turned on and set correct.

If you can not switch the fail safe off you need to configure it. Otherwise when you have glitches or switch the transmitter off you car can spin away on full throttle.

I have a sneaking suspicion the OP got an answer about 5 years ago.

I don't use fail safe for any reason. If I turn off the transmitter the car stops from signal loss. Fail safe is only for nitro and gas.

Get a cheap RTR transmitter and see there is no option to switch of the failsafe but will be programmed while binding.
Even my old Spektrum TX module of my Futaba T3VCS has no option to switch off the fail safe and so the failsafe need to be programmed with the right throttle position (in case of electric: neutral) while binding.

But hey, you know it all better

I've had an electric car run away when the transmitter turned off (low battery) was a Futaba 4px and R614 receiver

What esc were you using?????

A runaway has nothing to do with a transmitter low battery. It has to do with the ESC not receiving signal. Most newer esc have a cut off voltage that supplies power. BEC and if it drops below a certain point the power to the motor is cut off preventing a runaway. If you are using old school esc then then there is no safeguard and a runaway can happen. But a fail safe won't stop a electric car due to low voltage. No power! It was only meant for nitro or gas to bring the throttle servo back to a safe position in case of signal loss or low voltage. You have no servo for a throttle channel or external battery to power the receiver.

Beside he is clear that his transmitter did shut off due a low battery, the runaway has everyting to do with that.

Transmitter shuts off -> no signal -> failsafe pops in -> because it was not configured to the car it took whatever it had programmed last time (probably from another car)

But still you do not see that issue.
And yes, in his case it is possible to shut off the failsafe in the menu of the 4PX transmitter but but probably did forget it as it is something you normally do not care about. Again, not with all transmitters you can shut off the failsafe so it is something to be aware of.

The runaway was cause by the esc Not the transmitter or receiver My ESC will stop when power is low or the transmitter powers off (signal lost).. I don't have fail safe on my m11

I wonder with all your "I am right" posts if you are realy ignorant or if you are just trolling.

The ESC is just a dump thing and does what the receiver is telling him by the PWM signal. Yes, when there is no fail save in the system the PWM signal drops when the transmitter stops transmitting. But with a fail safe swiched on (post number 6 or 7 I try to explain that to you) the failsafe IN THE RECEIVER (!!!!) will become active and sends a pre programmed PWM signal to the ESC.

Do you know what's safer than the ESC going to neutral in fail safe conditions? Applying the brake. I've used the fail safe to apply brakes on electric cars before.