There are limits on the amounts of depreciation you can take per year for Passenger Automobiles.  Per the IRS, the limits you can deduct are based on the date you placed the automobile in service.

For example, a $50,000 vehicle placed in service in 2013, you are allowed to deduct $11,160 for the first year, $5,100 for the second year, $3,050 for the third year and $1,815 for the fourth and later years.

For more examples, review IRS Publication 946, How to Depreciate Property, page 61.