Sensors quality does have something to do with it, but regardless, you won't be able to get the accuracy and consistency from GPS you need for localizing a self driving vehicle.
Unless you get a DGPS unit (super expensive and require 3k subcription from satellites) you get north of 1m accuracy.
I ask this cause my wife's previous phone had consistently crappy GPS performance, losing satellite connection very often, getting stuck etc.
I never had such issues with mine, nor with her new one.