This paper presents an innovative concept of using Brayton cycle for the development of a lightweight, efficient, and reliable automotive heater for application in Army tracked vehicles. The system consists of a centrifugal compressor, combustion chamber, radial flow turbine, heat exchangers, a catalytic converter, a blower for discharge air, and fuel supply and starting mechanisms. The heater uses atmospheric air and can function with different blends of fuels such as JP-8, JP-5, DF-1, or DF-2. A catalytic converter is used to ensure complete and pollution free combustion. Heat exchangers are used to extract all the available thermal energy from the products of combustion. The system, in addition to its operation as heater, acts as an auxiliary source for electrical energy. A detailed thermodynamic analysis and design optimization was performed. For a given heat and electrical power output, the air-fuel ratio increased with operating pressure ratio. The system efficiency also increased with pressure ratio, and attained a maximum when the air-fuel ratio reached a stoichiometric condition. At this condition, the heater consumed only 5.54×10-7 m3/s (0.53 gallons/hr) of fuel to supply its rated heat load of 17.58 kW (60,000 Btu/hr). A continuous control of heat load was possible by changing the rate of combustion. In addition to high efficiency (more than 97 percent), the weight of the hardware was estimated to be within 10 kg (20 pounds).