Write off the entire car?

I am a W2 employee of a large corporation.  My wife is a Sole Proprietor of music studio in our home with over 40 students.  We recently purchased a new minivan mostly to help move large instruments and other items for her work.  In the past we have written off milage used for her work.  Our financial planner told us we could possibly write off the new vehicle in its entirety under the 179 deduction.  What do I need to know about this and is it really possible to do so? Thanks in advance.