The document discusses the performance of internal combustion engines using vegetable oils as fuel. It provides an overview of biodiesel production from vegetable oils and animal fats through a process called transesterification. The performance and economics of biodiesel from sources like soybean oil and waste vegetable oil are compared to petroleum diesel. While biodiesel blends perform better in some ways, production costs and limited raw material availability restrict its commercial use. The document also outlines advantages and disadvantages of using straight vegetable oils in engines.