Dog behavioral problem - can anyone help?

[Tippiechick]

If it only happens in the car and no one is being hurt by it, just accept that it's eccentricity at its best. Popping her collar when she's excited and agitated is only going to make things much worse. It won't help you...

If it's really that big of a deal, and Cesar Millan doesn't float your boat, just have your vet prescribe some Acepromazine or Valium and dose her up 30-45 minutes before getting in the car. Seriously. The meds are not expensive. Cut out the unnecessary trips and just dose her lightly each way.