A computing device may execute a routing application to perform operations including identifying a contextual parameter indicative of a quality preference for routing over segments of geographic mapping data, weighing the segments of geographic mapping data according to traffic score information indicative of the presence of the contextual parameter over the respective segments determined based at least in part on vehicle diagnostic data, and determining a suggested route for a vehicle from a current location to a destination location over the weighed segments of geographic mapping data based on the contextual parameter. The device may be further configured to receive a route request including the destination location for the vehicle; and display the route for the vehicle on a map including indications of the quality of the segments along the suggested route. To improve the routing, learning heuristics identify what diagnostic data variables correlate with presence of which contextual parameters.