The Popkov-Schütz two-lane lattice gas: Universality for general jump rates

We consider the asymmetric version of the Popkov-Schütz two-lane lattice gas with general jump rates, subject to the stationary measure being of product form. This still leaves five free parameters. At density 1/2 the eigenvalues of the flux Jacobian are degenerate. We compute the second order expansion of the average fluxes at density 1/2 and thereby identify the universality classes.