Tax Consequences of GM's 'Love It Or Return It' Promotion.
Plus this: Tax Implications: You may be subject to federal, state,
or local tax on any benefit paid. You should contact a tax
advisor/consultant if You have any questions regarding the tax
implications associated with this program.
So, if the car you return with 3.9K miles on it is worth $5K less than a new one, are you responsible for tax on the $5K "benefit"?