300: Systems of a Sort 6

Your teacher (me) is thinking about buying a new car. Presently, the cost of gas is $3.60 per gallon and he knows that he is going to commute to work each day and drive errands on the weekend ... about 300 miles per week.

He wonders whether or not to buy a Corolla or a Prius. Currently, he drives a Ford Ranger pickup truck, which is paid off but is starting to have some expensive repair bills. If he averages those costs, it's about $200 per month.

Option 1: The Corolla costs $16,800 (about $400/month) and gets roughly 36 mpg.
Option 2: The Prius costs $24,200 (about $570/month) and gets roughly 49 mpg.
Option 3: The Ranger is paid off but has repairs (about $200/month) and gets 21 mpg.
What should he do?

Prius:

Corolla: