本文探討贈送贈品策略對廠商的贈品價值、油品價格與利潤水準'消費者剩餘，以及社會福利有何影響？基於實務上廠商皆有從事贈送贈品的一致性行為，我們亦分析廠商是否有誘因從事共同贈送贈品策略？共同贈送贈品策略是否不利於消費者而且會降低經濟效率?本文的研究顯示：(1)贈品價值不會影響油品價格競爭，(2)贈送贈品策略可緩和油品價格競爭，使得廠商超額利潤，但不利於消費者剩餘。 然而，該策略可以增加社會福利因為廠商的超額利潤大於消費者的剩餘損失，以及(3)廠商並無誘因實施共同贈送贈品策略，因為有無實施該策略皆不會影響其超額利 潤水準。換言之，廠商的超額利潤與執行贈送贈品策略的方法無關。

This paper shows that a gift-giving strategy can be a profitable alternative that weakens price competition. We investigate the impact of differentiating a gift-giving strategy on the retail oil prices, profits, consumer’s surplus, and social welfare. We derive three results: (1) the gift value does not affect the retail oil price competition, (2) the gift­giving strategy mitigates the retail oil price competition and reduces consumer's surplus, and yet it increases social welfare because firms gain more than consumer's lose, and (3) there is no incentive for firms to explicitly coordinate and declare a joint industry-wide gift-giving strategy. In other words, firms’ profit is independent of the methods used by firms to execute the gift-giving strategy.