Although several studies have attempted to determine the mileage and time inefficiency of ridesourcing services due to concerns about traffic and environmental impacts of these services, all of them provide a point estimate, which does not reflect the uncertainties in the calculation of these estimates. As such this study aims to present the efficiencies as ranges, based on lower and upper limits by identifying drivers' daily activity schedule. Based on an analysis of 200 busiest RideAustin drivers’ trips data (around 282,037 trips over a 6 months period from 1 October 2016) the study finds that the mileage efficiency ranges from 44.3% to 71.6%, while time efficiency ranges from 42.8% to 58.4%. This means that for every 100-miles of a fare-payer passenger, drivers must travel an additional 40 to 126 miles empty. The heterogeneity of the efficiency at the driver level and the efficiency in the temporal dimension were also considered.