Modern environmentally beneficial methods of formulating motor gasoline often use ethers and/or alcohols as octane improvers. Thus, the thermophysical properties of these substances have become important in process engineering design, the simulation of gasoline blending operations, and engine operability. In all of these applications phase equilibrium properties are represented by thermodynamic models, which are derived from a combination of theory and experimental phase equilibrium data. This work seeks to quantify these models by careful measurement of key thermodynamic properties. For that purpose (vapour + liquid) equilibrium measurements on 2-methoxy-2-methylpropane, 2-ethoxy-2-methylpropane, and 2-methoxy-2-methylbutane with various alkanes, o-xylene, methanol, and water have been made using a static experimental method, at ether mole fractions of x = 0 to x = 0.5 over a temperature range of 293 K to 323 K.