Demand is a function of many factors, including individual ethical concern and cost. Exxon has spent billions to reduce both of these effects - ethical concern is reduced because of the seed of doubt about climate change, and cost is reduced because of political contributions. Exxon is a great example of a firm successfully privatizing profit and socializing cost.

it's the usefulness of the item in relation to its cost and the cost to run it. an electric heater is quite useful, but also takes a lot of electricity. if the electric company promises that i'll spend less on electricity for heating than i would on gas, then that does make a difference.

so yes, if exxon would promise that the gas prices are so low that i can afford an SUV, then i might be persuaded.