Autonomous driving has gained momentum in recent years. To help create a sustainable future, an autonomous vehicle should take into account its carbon footprint. This work proposes a new, portable, cost-effective carbon dioxide (CO2) emissions sensor installed in a Light Duty Vehicle (LDV), as a novel enabler towards carbon footprint aware autonomous driving. This work achieves the ability to report real-time metrics about the instantaneous CO2 emissions whilst satisfying non-invasive procedures (weight <1 kg) by means of Unified Diagnostic Services (UDS) compliant interrogators. The proposed solution is validated in compliance with European Union’s official emissions test procedures, and compared with other commercial off-the-shelf solutions. During the test, a 50 km trip divided in 3 driving cycles is performed to obtain the instantaneous CO2 emission, achieving a measuring rate similar to other commercial, non-portable and expensive alternatives.