This is for 91 Octane and the price is for a liter. There are 4.5 liters to a gallon. Unfortunately my car will only run on 98 which is even more expensive.
The McDonalds ad is for Georgie Pie, which used to be a popular fast food chain in New Zealand but they tried to expand too quickly and went under. The product was popular though and the company that owns the franchise rights for McDonalds picked it up.