The Internal Revenue Service has certified the Toyota Prius for model year 2005 as being eligible for the clean-burning fuel deduction. The certification means taxpayers purchasing the vehicle may claim a $2,000 deduction on their federal income tax. They must take the deduction in the year the vehicle is originally used. The IRS previously certified the Prius for model years 2001 through 2004, the Honda Insight for model years 2000 through 2004 and the Honda Civic Hybrid for model years 2003 and 2004.