Recently our group published a set of (p,rho,T) data for two (carbon dioxide + nitrogen) mixtures with a low carbon dioxide content (x(CO2) = 0.10, 0.15). These data showed larger relative deviations from the GERG-2008 equation of state than expected, specially at low temperatures, high pressures, and for the mixture with higher carbon dioxide content (x(CO2) = 0.15). In order to analyze whether the mentioned deviations from the equation of state increase with the carbon dioxide content, it was decided to measure the (p,rho,T) behavior of two additional mixtures with higher carbon dioxide molar fractions x(CO2) = 0.20, 0.50). The new experimental data show again an appreciable disagreement with the GERG-2008 equation of state at low temperatures and high pressures. Relative deviations, which depend on temperature, arise to 0.4% at 250 K and 20 MPa and to 0.24% at 275 K and 20 MPa for the x(CO2) = 0.20 and x(CO2) = 0.50 mixture, respectively. Second virial coefficients are calculated for the two new mixtures presented in this work and also for those presented in our previous paper. (C) 2012 Elsevier Ltd. All rights reserved.