Here’s the basic math. If your SUV is worthless, it will be worth junking when the cost per mile of feeding it gasoline is greater than the cost per mile for fuel plus the cost per mile of the depreciation on a new vehicle. (The Junking Moment will be higher if you also consider financing costs and insurance, but we’re going to keep it simple here.) Is It Time to Junk the SUV? - Registered Investment Advisor