LivingSocial offers a voucher for 25 cents off per gallon (20-gallon maximum) on your next fill-up at a participating Shell gas station for free when you sign up for Shell's Fuel Rewards program. (Existing members are not eligible for this deal. The discount applies to a single fill-up; you must dispense to the 20-gallon limit, or you forfeit any remaining savings for the other gallons.) Assuming you buy 20 gallons, that's a savings of $5. You must redeem your voucher by January 25, 2018. Deal ends January 23, 2018.

Note: Signing up for Fuel Rewards gets you instant Gold Status, so even after you've redeemed the above deal, you'll continue to receive at least 5 cents off per gallon. (You can increase your savings through various actions, like linking your rewards account to a credit card or booking travel through partner sites.) Click here for more information.