Energy eficiency in electric car

Internal combustion engines are relatively inefficient at converting on-board fuel energy to propulsion as most of the energy is wasted as heat. On the other hand, electric motors are more efficient in converting stored energy into driving a vehicle, and electric drive vehicles do not consume energy while at rest or coasting, and some of the energy lost when braking is captured and reused through regenerative braking, which captures as much as one fifth of the energy normally lost during braking.^[73][74] Typically, conventional gasoline engines effectively use only 15% of the fuel energy content to move the vehicle or to power accessories, and diesel engines can reach on-board efficiencies of 20%, while electric drive vehicles have on-board efficiency of around 80%.^[73]

Production and conversion electric cars typically use 10 to 23 kW·h/100 km (0.17 to 0.37 kW·h/mi).^[36][75] Approximately 20% of this power consumption is due to inefficiencies in charging the batteries. Tesla Motors indicates that the vehicle efficiency (including charging inefficiencies) of their lithium-ion battery powered vehicle is 12.7 kW·h/100 km (0.21 kW·h/mi) and the well-to-wheels efficiency (assuming the electricity is generated from natural gas) is 24.4 kW·h/100 km (0.39 kW·h/mi).^[76] The US fleet average of 10 l/100 km (24 mpg_-US) of gasoline is equivalent to 96 kW·h/100 km (1.58 kW·h/mi), and the Honda Insight uses 32 kW·h/100 km (0.52 kW·h/mi) (assuming 9.6 kW·h per liter of gasoline).^{[citation needed]}

The waste heat generated by an ICE is frequently put to beneficial use by heating the vehicle interior. Electric vehicles generate very little waste heat and resistance electric heat may have to be used to heat the interior of the vehicle if heat generated from battery charging/discharging can not be used to heat the interior. Electric vehicles used in cold weather will show increased energy consumption and reduced battery capacity and so decreased range on a single charge, for example the Mini E's range dropped by 30% in cold weather.^[77]