Thanks for your response winner.
I already thought of your suggestion. The only reason I am not tapping in to the battery compartment is because after I stop the motor from allowing the car to move forward, I still give the user the ability to reverse backwards. So I need to keep the battery powering the RC car.
My current circuit worked before with just one transistor, but for some reason it stopped working and I couldn't get it working again.
Thanks again and I appreciate any more input.