Frost & Sullivan, Mountain View, Calif., has released a study that tracks recent developments in alternative fuels and engines for automobiles. The report, Alternative Automotive Fuels and Engines Technologies, discusses progress the automotive industry has made in battery and fuel-cell technology. It also analyzes the advantages and disadvantages of alternative fuels such as ethanol, methanol, biodiesel, natural gas and liquefied petroleum gas. According to Frost & Sullivan, the demand for environment-friendly technologies has resulted in pressure on automakers to provide alternative fuels and engines to the public. Toyota Motor Corp., for example, recently began selling its new Prius, a hybrid car powered by both gasoline and electricity.