Modern spark ignition (SI) engines are designed for gasoline fuel, and therefore they are also referred to as gasoline engines. The use of different fuel types, such as hydrogen and liquefied petroleum gas (LPG), as single fuels in gasoline engines is possible due to the presence of an external ignition source. However, these fuels can have different effects on engine performance compared to gasoline. Hydrogen, a renewable and sustainable fuel, LPG, which is cheaper than gasoline, and gasoline, which is commonly preferred in the energy and power sectors today, are all important fuels to evaluate thermodynamically and exergoeconomically when used as single fuels in an SI engines. Assessing their efficiencies, sustainability, and economic impacts is crucial. In this paper, energy, exergy, and exergoeconomic analyses of three different fuel types (hydrogen, LPG, and gasoline) are conducted in a single-cylinder, four-stroke, air-cooled SI engines under stoichiometric conditions and at optimal ignition timings. The study is carried out at a fixed engine speed (1500 rpm) and stoichiometric conditions. Additionally, the ignition timing variation for each fuel occurs in intervals of 6° crank angle (CA). The results show that in a stoichiometric operating SI engines, the highest exergy efficiency is succeeded with gasoline, while the highest exergy destruction is obtained with hydrogen fuel. However, the exergoeconomic analysis results for hydrogen use in the SI engines are more favorable compared to gasoline and LPG. The specific exergy cost per unit of power for hydrogen is, on average, 33.4 % and 35.5 % lower than that of gasoline and LPG, respectively. Additionally, in the total cost rate, which includes enviro-economic costs, hydrogen shows results that are, on average, 53 % and 46.4 % lower compared to gasoline and LPG. This indicates that hydrogen use in a stoichiometric SI engines is more economically sustainable.