The car's regular fare is $35, not 50, or $70 return.. If you take 4 people in a car, that's $18 each both ways, and it will cost you $12 or so to park at a Ferry Terminal. That means it costs you an extra $14.50 each to bring your car; that's cheap.
November 18th is a Coast Saver day, that means $20 each way for your car, or $10 each for 4 people. This is not a special football sailing and is available regularly:
http://www.bcferries.com/promotions/coastsaver.html
So 4 people, car and passenger fares return: $82, or around $20 each.