Lift the bonnet of an electric car and there is no engine humming away, no exhaust pipe at the back and no gearbox to shift through. In their place sits a battery, a motor and some clever electronics. The result drives much like any other car but works in a fundamentally different way. Here is how an electric car works, from the battery to the wheels, what governs its range, and how its environmental footprint stacks up.
What an electric car is
An electric car, often shortened to EV for electric vehicle, is a car that stores energy in a large rechargeable battery and uses one or more electric motors to drive the wheels. There is no internal combustion engine burning petrol or diesel, which means no fuel tank, no exhaust and no tailpipe emissions while driving.
It is worth separating the terms. A fully electric car, sometimes called a battery electric vehicle, runs on electricity alone. A hybrid combines a petrol engine with a small electric system, and a plug-in hybrid has a larger battery you can charge from the mains and a backup engine. This guide focuses on the fully electric kind.
The battery and the motor
Two components do the heavy lifting.
The battery is the EV's fuel tank. It is a large pack made of many smaller cells, almost always using lithium-ion chemistry, the same family that powers phones and laptops, scaled up enormously. Its capacity is measured in kilowatt-hours (kWh): the more kilowatt-hours, the more energy stored and, broadly, the further the car can go.
The electric motor converts that stored electricity into movement. When you press the accelerator, the car's electronics send more current to the motor, which spins and turns the wheels. Electric motors have some natural advantages over engines.
- They deliver their pulling power, or torque, almost instantly, giving smooth, brisk acceleration from a standstill.
- They are highly efficient, turning a large share of the battery's energy into motion rather than waste heat.
- They have far fewer moving parts, so there is no clutch or multi-speed gearbox in the usual sense.
There is also a neat trick called regenerative braking. When you lift off or brake, the motor runs in reverse as a generator, slowing the car while turning some of its momentum back into electricity and topping up the battery. This is why EVs are particularly efficient in stop-start city driving, and why the principles of how batteries work matter so much to the whole package.
Charging
Charging an EV means moving electricity from the grid into the battery, and the speed depends on both the charger and the car.
| Charging type | Where | Typical use |
|---|---|---|
| Standard socket | Home three-pin plug | Slow top-up; many hours for a full charge |
| Home or workplace charger | Dedicated wallbox | Overnight or workday charging |
| Rapid or ultra-rapid | Public charging hubs | Big top-up in tens of minutes on a journey |
Two factors set the pace. The charger's power, measured in kilowatts (kW), is how fast it can deliver energy. The car's onboard limit is how fast it can accept charge. The slower of the two wins, so plugging a car that accepts modest power into a very fast charger does not make it charge any faster.
In practice, most EV owners do the bulk of their charging slowly at home overnight, which is cheap and convenient, and use rapid chargers mainly on longer trips. Charging overnight also fits neatly with a cleaner electricity system, a point we explore in our guide to renewable energy, because flexible demand helps balance the grid.
What affects range
Range, the distance a car can travel on a full charge, is the figure buyers worry about most, and it is not fixed. It moves with conditions.
- Battery size. A bigger pack stores more energy and generally goes further.
- Speed. Air resistance rises steeply with speed, so motorway cruising drains the battery faster than town driving.
- Driving style. Smooth, gentle acceleration stretches range; hard acceleration shortens it.
- Temperature. Cold weather reduces the battery's performance and increases energy use.
- Heating and cooling. Running the cabin heater in winter draws on the battery, since there is no engine waste heat to use, and can noticeably cut range.
An EV's quoted range is a guide measured under standard conditions. Real-world range depends on how, where and when you drive, much as a petrol car's miles per gallon does.
Lifecycle and emissions
Because an EV has no exhaust, it produces no tailpipe emissions, which improves local air quality. The fuller picture is its lifecycle footprint, the emissions across making, running and disposing of the car.
Two stages dominate. First, manufacturing, especially the battery, is energy-intensive, so an EV typically starts life with a larger carbon footprint than an equivalent petrol car. Second, use: an EV's running emissions depend on how the electricity is generated. Charged from coal power, the benefit shrinks; charged from a cleaner grid or home solar, it grows. The International Energy Agency and others find that, over a typical lifetime, EVs are generally lower-carbon than petrol or diesel in most countries, and the gap widens as electricity grids get cleaner. End-of-life battery recycling is improving and will further reduce the footprint over time.
For UK buyers, GOV.UK is the place to check current grants, charging-point support and any tax differences, since these change from year to year. Choosing an EV is one of the bigger levers an individual can pull on their carbon footprint, provided the electricity behind it is reasonably clean.
The bottom line
An electric car swaps the engine and fuel tank for an electric motor and a lithium-ion battery, drawing energy from the grid and recovering some of it through regenerative braking. Charging speed depends on both the charger and the car, while range varies with battery size, speed, driving style and weather. With no tailpipe emissions and a lifecycle footprint that improves as grids get cleaner, an EV is, for most drivers, a lower-carbon way to get around, and an increasingly practical one as charging networks grow.