QUICK ANSWER
A mild hybrid uses a small electric motor to help the petrol engine but can’t drive on electricity alone. A full hybrid can drive short distances on electric power and charges itself. A plug-in hybrid has a bigger battery you charge from a socket for longer electric driving. An EV runs on electricity only, with no petrol engine at all.
Car makers use these labels constantly, and they are easy to mix up. The difference matters, because it changes how much fuel you use, whether you need a charger, and what the car costs to run. Here is a plain-English breakdown.
Mild hybrid (MHEV)
A mild hybrid adds a small electric motor and battery, usually on a 48-volt system, to a normal petrol or diesel engine. The motor helps when you pull away and lets the engine switch off smoothly when you stop or coast. It recovers energy when you brake.
What it cannot do is move the car on electricity alone. Fuel savings are modest, but there is nothing to plug in and the car drives exactly like a regular one.
Full hybrid (HEV)
A full hybrid, sometimes called a self-charging hybrid, has a larger battery and motor. It can drive short distances at low speed on electric power alone, such as in traffic or car parks, and switches between electric, petrol or both automatically. The battery charges from braking and from the engine, so you never plug it in.
Full hybrids tend to save the most fuel in stop-start city driving, and less on long motorway runs.
Plug-in hybrid (PHEV)
A plug-in hybrid has a much bigger battery that you charge from a home socket or public charger. On a full charge it can usually cover a useful daily distance on electricity alone, then switches to petrol for longer trips.
PHEVs can be very cheap to run if you charge them regularly and mostly do short journeys. If you rarely plug in, you end up carrying a heavy battery around and may use more fuel than a regular hybrid.
Battery electric vehicle (EV)
An EV has no petrol engine. It runs entirely on a large battery and one or more electric motors, and you charge it at home, at work or at public chargers. EVs have no tailpipe emissions, fewer moving parts and usually lower running costs, but they cost more upfront in many markets and long trips need some charging planning.
Side-by-side comparison
| Mild hybrid | Full hybrid | Plug-in hybrid | EV | |
|---|---|---|---|---|
| Drives on electric only? | No | Short distances | Yes, for a useful range | Always |
| Needs plugging in? | No | No | Yes, to get the benefit | Yes |
| Petrol engine? | Yes | Yes | Yes | No |
| Best for | Drivers wanting a small saving with no change | City and mixed driving | Short daily trips with home charging | Drivers with easy access to charging |
Which one is right for you?
- No home charging and lots of motorway driving: a mild or full hybrid keeps things simple.
- Mostly city driving, no charger: a full hybrid usually saves the most fuel.
- Short daily commute and a driveway charger: a plug-in hybrid or an EV can cut running costs sharply.
- Easy charging at home or work and you want the lowest running costs: an EV.
Local tax rules, fuel and electricity prices, and incentives vary widely by country and change often, so compare the real running costs where you live before deciding.
Frequently asked questions
Do hybrids need special servicing?
They are serviced much like regular cars, though the hybrid system should be checked by a qualified technician. Brakes often last longer because the motor does some of the slowing down.
How long do hybrid and EV batteries last?
Batteries lose capacity slowly over time, and many makers offer long battery warranties. Check the specific warranty for any car you are considering.
Is a self-charging hybrid really free to charge?
The battery is charged by braking and by the petrol engine, so the energy ultimately still comes from fuel. It is simply used more efficiently.
Can I drive a plug-in hybrid without charging it?
Yes, it will run on petrol like a normal hybrid, but you lose most of the running-cost benefit.
Sources
- FuelEconomy.gov (US Department of Energy): how hybrids, plug-ins and EVs work
- International Energy Agency: global electric vehicle research