You should also add in the resale or trade in value. Trade in value for 2005 Prius in excellent condition is around $11,000 while trade in value of Corolla in excellent condition is around $6,000. So after 5 years, the Prius still holds about $5,000 value over the Corolla which nullifies most of the price difference from the initial purchase. Also, the Prius has held on to more of it's value (30 to 50%) versus the Corolla (15 to 30%).
Just saying, if you want to do a detailed analysis you should include resale cost since most people do use their existing cars as trade ins when they purchase new cars.