Are you asking if it can turn all the way left and right with the Z590M Servo? if so then no. Are you running a rechargeable RX pack? That can help but your best bet is to invest in a decent high torque metal geared ball bearing servo. A decent priced one is the 645MG at 6V it is rated near 130 oz of torque. I use the JR 650 as it is rated close to 160 oz. NO steering servo will turn wheels on the fround using a dry cell pack.
Invest:
6v RX pack, come in Mah ratings from 1100 to 2700mah. bigger the current the longer it will last.
Servo: Research for that. Get a decent one. look at the specs and make sure it is a high torque metal geared ball bearing servo. The transit time isn't that big of a deal if you bash but racing you might.