Work reported in this paper is the continuation of a previous work (Atilhan et al. J. Chem. Eng. Data 2011, 56, 212-221) and reports measurements of density and phase envelope characteristics of three synthetic natural gas-like mixtures. These mixtures consist of primarily 0.9000 methane in mole fraction and variable amounts of ethane, propane, 2-methylpropane, butane, 2-methylbutane, and pentane as well as the presence or absence of nitrogen and carbon dioxide. A high-pressure single-sinker magnetic suspension densimeter was used to measure the density of the mixtures along three isotherms at (250, 350, and 450) K with pressures up to 150 MPa. Density measurements are compared to the GERG04 and AGA-8 equations of state, which are the two leading models used for natural gas density predictions. Predictions from both equations have a similar agreement with the data, yet it is observed that GERG04 model shows better performance in predictions with deviations less than around 0.2 % at different temperatures (T = 350 K and T = 450 K) and pressures (p > 20 MPa). An isochoric apparatus was used for phase envelope experiments, and the data are compared to several cubic biparametric, cubic triparametric, and molecular-based equation of states. Equation-of-state predictions for the mixtures and comparison with the experimental data are shown. Equation-of-state predictions show substantial deviations around the entire phase envelope for the third mixture, in which the nitrogen and carbon dioxide have not been included.