According to 26 U.S. Code § 280F - Limitation on depreciation for luxury automobiles the first year's depreciation expense for a newly procured vehicle should be prorated over the tax year based on the in service date not to exceed the limitations spelled out in IRS Rev Proc 2014-21
For passenger automobiles the 2014 Tax Year Amount is:
1st Tax Year $ 3,160
2nd Tax Year $ 5,100
3rd Tax Year $ 3,050
For trucks and vans the 2014 Tax Year Amount is:
1st Tax Year $ 3,460
2nd Tax Year $ 5,500
3rd Tax Year $ 3,350
This of course is separate and distinct from new vehicle acquisition from a manufacturer that entitles business owners to the provisions of 26 U.S. Code § 179 - Election to expense certain depreciable business assets.
For Lease Inclusions be sure to reference Table 3 of IRS Rev Proc 2014-21.
All I can say about this is that if you are fooled into messing with these tables you will get dinged now that the IRS' new modernized e-file system is fully functional. Not to worry though as these numbers are updated annually to account for inflation.