Gasoline-to-Electric Vehicle Conversion as a Circular and Safety-Critical Pathway for Transport Electrification: A Structured Critical Evidence Review

Background: Gasoline-to-electric vehicle conversion may extend the service life of mechanically sound vehicles, but it introduces electrical, structural, environmental, economic, and regulatory risks. Objective: To identify the conditions under which conversion is safe, evidence-based, and justifiable. Methods: A structured critical evidence review searched Scopus, Web of Science, IEEE Xplore, ScienceDirect, SpringerLink and SAE Mobilus for mainly English-language material published from 2010 to 22 July 2026. Standards, official reports, and citation searches supplemented the database search. PRISMA 2020 informed transparent reporting, but the review is not claimed to be a registered or fully reproducible systematic review because contemporaneous database export files, duplicate-removal records, and screening logs were not retained. The revised bibliography contains 94 traceable references; unavailable stage-specific counts were not invented. Heterogeneous evidence was critically synthesized without meta-analysis. Results: Direct retrofit evidence remains limited. A documented Smart conversion used real-world data after 100,000 km of prior service and reported 16% lower life-cycle CO2-equivalent impact than a new battery-electric comparator under its specific assumptions. A Maruti 800 design study reported a 10.24 kWh battery, a 10 kW motor, 10 kWh/100 km simulated energy use, and an estimated USD 4370 conversion cost, but there was no physical validation or road approval. A worked, hypothetical delivery-van case demonstrates risk-adjusted economics, life-cycle screening, sensitivity analysis, and mandatory regulatory gating. Conclusions: Conversion is defensible only for suitable donor vehicles with documented structural assessment, battery retention, fail-safe controls, roadworthiness verification, credible after-sales support, and a lawful approval pathway.