With respect to depreciation of business assets, you can do anything that is permitted by IRS regulations, although good argument can be made for maintaining a consistent depreciation policy.
While assets of different classes (vehicles, office equipment, buildings, etc.) will have required useful lives, you have a great degree of flexibility in choosing depreciation methods. You may choose to take advantage of the increased cap on Sec. 179 expensing of assets rather than depreciating over their useful lives.
For more authoritative information, please refer to IRS Pub. 946 How To Depreciate
Property.