Assessing well-to-wheel decarbonization pathways and carbon pricing for a mixed-powertrain ride-sourcing fleet

Although transitioning to electric mobility is critical, decarbonization pathways for mixed-powertrain ride-sourcing fleets, particularly those already dominated by hybrid electric vehicles, remain underexplored. This study assesses well-to-wheel emissions and carbon pricing implications for a regional ride-sourcing fleet through a policy-anchored scenario-simulation framework. Within this framework, a hybrid ARIMA-LSTM model is employed to forecast mileage demand as a key input, which is then integrated with time-varying emission factors and national electrification pathways to evaluate emission and carbon-fee outcomes across scenarios. Five scenarios were established, ranging from a baseline of 100% internal combustion engine vehicles to policy-driven targets of 30%, 60%, and 100% electric vehicles by 2030, 2035, and 2040. Results reveal a significant divergence: while tank-to-wheel emissions decrease by 33%, 62%, and 100% respectively, reductions are limited to 17%, 29%, and 44% when well-to-wheel emissions are taken into account. Furthermore, analysis confirmed that fleet electrification would effectively mitigate future expenditures for carbon fees. Regarding electricity emission factors, estimations showed that faster grid decarbonization leads to significantly greater cumulative reductions. This demonstrates that vehicle electrification alone is insufficient for deep decarbonization; its benefits are significantly enhanced only when combined with parallel grid decarbonization, producing a compounding reduction effect across the well-to-wheel boundary.Implications: This study demonstrates that for mixed-powertrain fleets, relying solely on tank-to-wheel metrics overstates the achievable decarbonization under full electrification, indicating a 100% reduction when the actual well-to-wheel reduction is only 44%. Consequently, policymakers must synchronize vehicle electrification mandates with accelerated grid decarbonization to bridge the gap between local zero-emission targets and actual lifecycle reductions. Furthermore, the analysis confirms that fleet electrification serves as a critical financial hedge against rising carbon prices. These insights provide stakeholders with a realistic framework for integrating transportation strategies with energy policy to ensure holistic long-term sustainability.