Ethers are usually used as gasoline additives, and now 2-methoxy-2-methylpropane (MTBE) is the most widely used fuel additive. The speed of sound in MTBE with a specified mass purity higher than 0.990 (GC) was measured by the Brillouin light scattering method in the temperature range of 293.15673.15 K and for pressures up to 10 MPa, including saturated liquid/vapor, liquid, and supercritical fluid. The correlations for the speed of sound in saturated liquid/vapor and liquid were proposed by employing the experimental results. Comparing the calculated results with the experimental data, the average absolute deviations are 0.50% for saturated liquid, 0.20% for saturated vapor, and 0.24% for liquid. The tendency of speed of sound to temperature and pressure was also analyzed.