Foxy

Yeh, if your receiver battery runs out and you don't have a strong spring on the throttle servo to return it if it loses power (this is the one situation where the built in failsafes can't help you), then you will lose all control of the car. Many tracks require racers to have a throttle return spring regardless what kind of failsafe technology is in the car, it is a good mechanical safeguard. You can double up a couple of elastic bands until you find a suitable spring. The trick is to make it strong enough so that with the throttle full, when you turn off the car, the throttle returns to neutral, but no stronger, as that will hurt the servos (especially if they're crap).