If I spend $10,000/yr in fuel and my marginal tax rate is 20%, that means I save $2,000/yr on taxes. Overall I’m -$8,000 in fuel expense reduced by the tax deduction it got me.
If I spend $5,000/yr in fuel with the same marginal tax rate, that means I save $1,000/yr on taxes. Overall I’m -$4,000 in fuel expense reduced…