[oil pan 4]

Vehicle to grid isn't happening for a very long time.

First problem.
All of the vehicles on the road today or that are going to be built in the near future are designed to only have power flow from the grid to the battery.

Then it appears that around half of people who have plug in cars charge with 120v power. That level of connection isn't even worth trying to push power on to the grid.

You have to convince people that this isn't going to leave their vehicles drained when they need it and when the first time someone gets stuck, can't drive their car to work or runs out of power on the road because of vehicle to grid it's over for that person.
People have to be convinced this isn't going to wear out their battery faster.

Then you will have regional and local brand trust issues. For example AEP is a power company on the east coast that is universally hated by everybody. No one is going to do anything to help them.

Who is going to pay for it how is it going to work, when is it going to work. All questions answered only when the auto makers sit down with the power companies.
So far they have shown 0 interest in working with each other.