Drivetrain series · Part 1 of 4
BEV, full hybrid, plug-in: the one difference from which all others follow
«Hybrid», «electrified», «EV» — in the showroom and in the classified ad these words are thrown around as if they meant the same thing. They do not. Technically, more separates a full hybrid from a plug-in than a petrol car from a diesel. This series takes apart the three drivetrains that get confused most often, and it does so for the purchase decision, not for the statistics. How these same categories distort the market figures has its own post further down. Here the question is what actually happens under the bodywork.
Part 1 lays out the technology. Part 2 covers advantages, disadvantages and sensible use. Part 3 deals with the risks and what to watch for when buying. Part 4 follows in November with the analysis that only makes proper sense then: winter driving.
The one question that decides everything: where does the energy come from?
A car needs energy to move. The only difference between the drivetrains that really counts is where that energy comes from. Everything else — cost, range, servicing, emissions — follows from it.
- BEV (battery electric): The energy comes 100 per cent from the socket. The battery is the only store. No tank, no combustion engine.
- Full hybrid (HEV): The energy comes 100 per cent from the tank. The electricity in the small battery is not fed in from outside but recovered while driving — under braking and from the surplus of the combustion engine. You never plug this car in. The electric side merely recycles energy that would otherwise escape as heat, and makes the petrol engine more economical. At its core a combustion car that wastes less.
- Plug-in hybrid (PHEV): Both. You can charge energy from the socket and refill from the tank. Which source dominates depends solely on whether you charge. Charge daily and you mostly drive electrically. Never charge and you are hauling a heavy petrol car around.
That explains the core. The rest is consequences.
The battery: orders of magnitude, not nuances
Battery capacity separates the three cleanly, by a factor of roughly fifty:
- A BEV carries roughly 40 to over 100 kilowatt hours.
- A plug-in around 10 to 25 kilowatt hours — enough for everyday use, too little for a long journey without the combustion engine.
- A full hybrid about 1 to 2 kilowatt hours. That is a buffer, not a traction battery.
These sizes explain almost everything else: range, price, weight.
Purely electric: how far in practice
- BEV: depending on the model roughly 300 to 600 kilometres, less in winter — see Part 4.
- Plug-in: 40 to 140 kilometres under WLTP, in reality more like 30 to 90. Enough for the commute, provided it is charged.
- Full hybrid: no meaningful electric range. A few hundred metres to a few kilometres in bursts, at city speeds, then the combustion engine cuts in. Toyota speaks of up to 80 per cent electric driving in the city — that is a share of time, not a distance.
How much technology sits under the bodywork
Here the picture flips. Electric is mechanically simple, hybrid is complicated.
A BEV has one system: battery, power electronics, one or two electric motors, a fixed reduction gear. No gearbox, no clutch, no exhaust, no classic oil change, hardly any wearing parts. The simplest drivetrain a car can have.
A full hybrid and a plug-in carry two complete systems side by side: a full combustion engine with gearbox, exhaust system and oil circuit — plus an electric motor, a battery and power electronics. Both need servicing, both can fail. That is the price of flexibility, and it returns in Parts 2 and 3: in servicing, reliability and resale.
Electric is the simplest drivetrain, hybrid the most complicated. The combustion car with a plug carries two drivetrains at once.
Why electric is cheaper per kilometre
An electric motor turns roughly 70 to 90 per cent of the charged energy into forward motion. A combustion engine manages 20 to 30 per cent; the large remainder is lost as heat. The full hybrid recovers part of these losses through regeneration and pushes the combustion engine into a somewhat better efficiency range — which is why it saves above all in the city, where there is frequent braking. On the motorway, where there is hardly any regeneration, the advantage shrinks.
The three at a glance
| BEV | Full hybrid | Plug-in | |
|---|---|---|---|
| Energy source | socket | tank | socket and tank |
| Battery | 40–100+ kWh | 1–2 kWh | 10–25 kWh |
| Electric range | 300–600 km | none (bursts) | 40–140 km WLTP |
| Gets charged | yes, always | never | yes, pointless otherwise |
| Drivetrain | one system | two systems | two systems |
Two special cases in between
Mild hybrid (MHEV): a 48-volt helper that supports the combustion engine when pulling away and recovers a little under braking. It cannot drive electrically. Technically closer to a start-stop system than to an electric car — even where «hybrid» is written on the boot lid.
Range extender (REEV): always drives electrically, but carries a small combustion engine on board that never drives the wheels and only generates electricity for the battery. Socket plus tank, but the driving feel of an electric car. Back on the market in Switzerland, for instance at Leapmotor.
What comes next
That sets the technical foundation. Part 2 deals with advantages and disadvantages and the question of which drivetrain suits whom — and whom it expressly does not. Part 3 takes on the risks: the plug-in trap of a battery that is never charged, the servicing of two systems, what to watch for when buying used. Part 4 arrives in November, when the question turns practical: what cold does to range, charging power and consumption.
Basis: general drivetrain engineering; battery and range figures given as market-typical ranges, not model-specific. Figure on the electric driving share of the full hybrid from Toyota. The classification of the categories for the Swiss market rests on the data of this site (auto-schweiz, ASTRA/IVZ register).
