Section 179 or Special Depreciation Allowance for Self Employed Van Purchase

Hi there, I have been trying to figure this out myself but having trouble.  I bought a van for $37,000 and am self-employed with a net income of $18,000.  I file jointly with my husband who gets 1099R income.  I am confused about whether Section 179 deduction or Special Depreciation would be better for me.  SD gives me a bigger refund but puts my net income into a negative situation.  Section 179 gives me a much smaller refund but puts my net income at $0.  My income is variable, and so I don't know if I will make the same amount this year as last year, but I can always do a catch-up contribution to a 401k in the future to reduce my taxable income.  I don't think either changes our tax bracket for this year.  I am tempted to go for the higher refund, but maybe it would be more prudent to have a depreciation deduction next year.  Any advice is appreciated.