In　this　paper,　we　study　the　phenomenon　of　concentration　and　the　formation　of　delta　shock　wave　in　vanishing　adiabatic　exponent　limit　of　Riemann　solutions　to　the　Aw-Rascle　traffic　model.　It　is　proved　that　as　the　adiabatic　exponent　vanishes,　the　limit　of　solutions　tends　to　a　special　delta-shock　rather　than　the　classical　one　to　the　zero　pressure　gas　dynamics.　In　order　to　further　study　this　problem,　we　consider　a　perturbed　Aw-Rascle　model　and　proceed　to　investigate　the　limits　of　solutions.　We　rigorously　proved　that,　as　the　adiabatic　exponent　tends　to　one,　any　Riemann　solution　containing　two　shock　waves　tends　to　a　delta-shock　to　the　zero　pressure　gas　dynamics　in　the　distribution　sense.　Moreover,　some　representative　numerical　simulations　are　exhibited　to　confirm　the　theoretical　analysis.