Roy Smith 
2017 Toyota Prius Prime Hatchback Advanced 4dr Hatchback (1.8L 4cyl gas/electric hybrid CVT)
Owners Manual sugested use 4 gallons of gas a year
 I laughed when I read about refreshing the gas yearly. But I now have had the car three months and still have over half of the tank of gas the dealer provided when I bought the car, and I have driven 1,200 miles. As I have discovered most of my daily travel involves trips of less than 30 miles. The car claims a 25 mile range but the battery meter has at times registered capacity over 30 miles. I have also not seen any measurable change in my electric bill. I have no Idea how many miles I will be able to travel before I need to put gas in the car. This is great and the car is so quiet when running on electric! Roy Smith