Which method to use? Aversive-Based Training, which is sometimes called Traditional Method, or Reward-Based Method? The former uses the addition or removal of something unpleasant. The latter adds something good for desirable behaviour and removes something good for undesirable behaviour.
For training to be an effective an unwanted behaviour must be replaced by a desirable behaviour. If this does not begin to happen right away, you know your technique is not an efficient one.
Animals learn via action and result. If I jerk on your choke chain to stop you from pulling, you may hesitate to catch your breath, but very often the jerking does not change the behaviour. This method of training can be very traumatic for a dog, but even if it is not, it often has little or no effect as a training method. If your dog is still moving forward on a tight leash, the pulling is being reinforced by the simple fact that he is getting to go where he wants to go.
Your puppy does not like travelling in the car: If you catch the puppy’s leash in the car door, all you are teaching your anxious pup is that car rides really are unpleasant. He is anxious and cannot even move around to have a little relief from his anxiety. You need a friend or partner to assist with training. Using distraction, a marker and treats, they can gently reassure your pup and, using positive reinforcement TEACH him what good behaviour is while you drive.
Perhaps the traditionalists among us will say this is all too like a soft Montessori method. It is, however, the better way to teach your pup what you would prefer him to do.
Reward-Based Training is far more efficient and effective than any Aversive-Based training can be.