This is a downside of electric cars. According to one report, producing the average electric vehicle generates around 8.8 tonnes of CO2, compared to 5.6 tonnes for the equivalent petrol car. Around 43 per cent of this is from producing the batteries. This is balanced out over the car's life, however, a medium-sized family car will produce around 24 tonnes of CO2 over its life, while an EV will produce around 18 tonnes. Around 46 per cent of an EV's total carbon footprint is generated at the factory. It's worth noting, though, that many manufacturers are introducing renewal energy sources to their plants. And some electricity suppliers, such as Ecotricity (which provides EV charge points at motorway service stations), use renewable energy.