Toyota will bring hybrid electric automobiles to market next year priced at $27,000 (this includes a $6,750 federal tax credit). At $1.89 per gallon of gasoline, it will take 11 years to recoup the difference in price between a base model Toyota Camry and its four-cylinder gasoline-only counterpart. The price difference is $4,180. If the hybrid vehicle is driven for 15 years, what is the internal rate of return on the extra investment in the hybrid?