Methods and systems are described that enable world geodetic system (WGS) to cartesian coordinate conversion for driving. A path of a vehicle comprising lane-group segments (LGSs) is received. The LGSs comprise respective origins in WGS coordinates, respective path points in WGS coordinates; and respective groups of constants. For a first of the LGSs, global cartesian path coordinates are calculated, based on modified Bowring techniques, for the path points of the first LGS. The coordinates are calculated using the constants of the first LGS and respective differences between the path points of the first LGS and an origin of the first LGS. The vehicle can navigate along the path using the global cartesian path coordinates calculated for the first LGS. By using modified Bowring techniques and pre-calculated constants for each LGS of the path, accuracy can be maintained over long distances and across boundaries without requiring substantial computational overhead.