Marketing and all things related

Every merchant and their dog has an affinity program these days. You give away your personal data to your local grocer, and in return you get cat food coupons. But the real deal these days is gasoline. Even time you spend X dollars with merchant Y, you earn ten cents off per gallon of gas. You can even horde these savings, until a $ 47.00 fill-up of $ 2.46 per gallon high octane juice is absolutely free! Our wife thinks this is wonderful, and we do not disagree. We are puzzled, however, that she now plays the gas gage like a roulette wheel. In the past, she would insist on a refill every time the tank hit the half-way mark. Now she waits for the warning light to kick-in within coasting distance of the gas station. Can you name another affinity program reward that smells bad and readily combusts?