Many cargo van owners have pondered the choice of depreciation or mileage. The key to the greatest benefit is thinking long term. If you choose depreciation, you can't change to mileage later.
Effective January 1, 2007 the standard mileage allowance is 48.5 cents per mile for business miles driven. If you drive a total of 500,000 Sprinter miles at the current rate, you'll have total deductions of $242,500 over five +/- tax years. Will the depreciated cost of your van, plus allowable operating expense deductions equal that much? You should already have that answer if you've forecast your expenses properly.