The United Kingdom aims for an 80% reduction of carbon dioxide emissions by 2050 compared to the levels in 1990. If the transport sector will be able to achieve its share is questionable. This paper aims to analyse how the pace of Battery Electric Vehicles transition and driving behaviour of Plugged in Hybrid Electric Vehicles users can impact the Green House Gas emissions reduction performance of the UK transport sector in meeting the carbon targets by 2050. A reference model for different types of vehicle classes is developed to determine the emissions contributed. The growth of each vehicle class, improvements in efficiency of Electric Vehicles and low carbon fuel targets are projected until the year 2050. Scenario-based models are then developed to analyse how varying the pace of Battery Electric Vehicle transition and hybrid car user driving behaviour would impact the emissions reduction performance. The results of the paper show that the current pace of Battery Electric Vehicle adoption is insufficient for the UK transport sector to achieve the 4th to 7th carbon budgets, due to the slow reduction in Internal Combustion Engine Vehicles. For the 8th and final carbon budgets, emissions may still exceed the carbon budget despite transiting to Electric Vehicles if hybrid car users continue to drive on gasoline modes. The proposed model will serve as a useful reference to assess if the current UK transport strategies and policies suffice and if more actions are necessary to meet the 2050 carbon target.