Safe vehicle localization is the key technology for the advanced driving assistance systems (ADAS).The safely assured vehicle locations generated by localization unit as part of the electrical / electronic (E/E) subsystems inside the vehicle needs to be validated and certified for fully autonomous driving cars in the future.The global navigation satellite systems (GNSS) is a good instance for the perception of the vehicle location,since it can provide all day along and almost everywhere vehicle localization functionality.But GNSS is easily to be affected by the environmental conditions along the vehicle driving route.The GNSS quality itself is assured by the GNSS service provider at the signal in space (SIS) part settled according to the GNSS standards and specifications.But for the ground-based applications,the GNSS performance itself is not assured,the environmental condition effect varies in different operation scenarios.The accuracy quality as the basement of the whole quality of service (QoS) of GNSS,is the most required performance in many aspects.This paper describes the accuracy requirement of the vehicle safe localization concept at first,then the accuracy evaluation in different coordinate systems are evaluated,an appropriate coordinate to represent the dynamic movement of the vehicle is used,the error mode to describe the 2D accura-cy for safe vehicle localization is proposed.Finally,an error mode as the base for accuracy evaluation method for urban operation scenarios with the consideration of bi-directional error mode is suggested for safe vehicle localization performance analysis.