Types of Electric Vehicles: BEV, PHEV, HEV, Mild Hybrid and FCEV Explained

In short

• "Electric vehicle" covers a ladder of designs, from a mild hybrid with a small 48 V motor to a battery electric vehicle with no engine at all.
• The two questions that sort them: can it plug in? and can the electric motor drive the wheels on its own?
• Hybrids (MHEV, HEV) charge only from the engine and braking. Plug-ins (PHEV, EREV, BEV) charge from the grid. Fuel cell vehicles (FCEV) make their electricity from hydrogen.
• Each type puts the engineering effort in a different place: energy management in hybrids, the battery pack, charging and thermal system in BEVs, the stack and hydrogen storage in FCEVs.

What counts as an electric vehicle?

An electric vehicle is any vehicle in which an electric motor provides some or all of the drive. That definition is broad on purpose. A car that uses a motor only to restart the engine and help it accelerate is "electrified". So is a scooter with nothing but a battery and a hub motor. Between those two sit several designs, and the names for them (HEV, PHEV, BEV and so on) come from industry terminology such as SAE J1715, the SAE's glossary of hybrid and electric vehicle terms.

Two questions sort almost every vehicle into the right box:

1. Can it plug in? If the traction battery can be charged from the grid, it is a plug-in (PHEV, EREV or BEV). If not, it is a conventional hybrid (MHEV or HEV), and every unit of energy ultimately comes from the fuel tank.
2. Can the motor drive the wheels on its own? A mild hybrid cannot. A full hybrid can, but only briefly at low speed. A PHEV can for tens of kilometres. A BEV has nothing else.

The size of the traction battery follows from those answers, which is why it is the clearest single number for telling the types apart.

The types of electric vehicles at a glance

Type	What drives the wheels	Plugs in?	Electric-only driving	Typical traction battery
Mild hybrid (MHEV)	Engine, with motor assist	No	None	About 0.3–1 kWh, usually 48 V
Full hybrid (HEV)	Engine and/or motor	No	Short distances at low speed	About 0.8–2 kWh, a few hundred volts
Plug-in hybrid (PHEV)	Engine and/or motor	Yes	Tens of km, then works as a hybrid	About 8–35 kWh
Range-extended EV (EREV)	Motor only; the engine just generates electricity	Yes	Tens to 200+ km	About 20–45 kWh
Battery electric (BEV)	Motor only	Yes	Always	About 25–110 kWh for cars; 1.5–5 kWh for two-wheelers
Fuel cell electric (FCEV)	Motor only; the fuel cell generates electricity from hydrogen	Usually no	Always (on hydrogen)	About 1–2 kWh buffer; energy is stored as hydrogen

The battery figures are indicative ranges for current passenger vehicles, not limits. They are useful for a sense of scale: a big BEV pack holds roughly a hundred times the energy of a full hybrid's battery.

Mild hybrid (MHEV)

A mild hybrid adds a small motor-generator, usually a belt-driven starter-generator on the engine, and a small battery. The U.S. Department of Energy's Alternative Fuels Data Center describes the key limit plainly: mild hybrid systems cannot power the vehicle using electricity alone. What they do is:

• switch the engine off at stops and restart it smoothly,
• add a little torque when pulling away, so the engine works in a more efficient region,
• recover some braking energy into the battery.

Many mild hybrids run at 48 V instead of the usual 12 V. The reason is simple electrical arithmetic. Power is voltage times current, so delivering 10 kW at 12 V needs over 800 A, while 48 V needs about 210 A, which is practical for ordinary cables and connectors. Staying at 48 V also keeps the system below the voltage at which the full set of high-voltage safety measures applies, so it is much cheaper to add to an existing car than a high-voltage hybrid system. The fuel saving is modest, and it is largest in stop-and-go city driving.

Full hybrid (HEV)

A full or "strong" hybrid has a larger battery and motor that can move the car on electricity alone for short distances at low speed. It still cannot plug in: the battery is charged only by the engine and by regenerative braking, where the motor runs as a generator when you slow down. The Toyota Innova Hycross hybrid sold in India, for example, lists a 168-cell nickel-metal-hydride battery. At about 1.2 V per NiMH cell, that is roughly 200 V nominal, far above a mild hybrid's 48 V.

How the engine and motor are connected matters more than the battery. There are three classic architectures:

• Series: the engine only turns a generator. The motor alone drives the wheels, so the engine can run at its most efficient speed regardless of road speed. Energy is converted twice (mechanical to electrical and back), which costs efficiency at steady highway speed.
• Parallel: engine and motor are both mechanically connected to the transmission and can drive the wheels together. The DOE notes this is the most common hybrid design. It is efficient on the highway but the engine speed is tied to road speed through the gearbox.
• Series-parallel (power split): a planetary gear set splits engine power between a direct mechanical path and a generator, while a second motor-generator adds or absorbs torque. This acts like a continuously variable transmission and lets the controller choose the best mix at every moment. Toyota's hybrid system is the best-known example.

The hard engineering problem in any hybrid is the energy management strategy: the control logic that decides, many times a second, how much power comes from the engine and how much from the battery, while keeping the battery's state of charge in a safe band. It is a classic optimisation and controls problem, usually developed in MATLAB/Simulink and validated on hardware-in-the-loop rigs.

Plug-in hybrid (PHEV)

A plug-in hybrid has the same building blocks as a full hybrid plus a much larger battery, an onboard charger and a charge port. According to the AFDC, a PHEV typically runs on electric power until the battery is nearly depleted and then switches automatically to using the engine. Engineers call these two phases:

• Charge-depleting mode: the vehicle drives mainly on battery energy, and the state of charge falls.
• Charge-sustaining mode: once the battery reaches its lower limit, the car behaves like a full hybrid and holds the state of charge roughly constant.

The catch is behavioural, not technical. A PHEV that is charged every night can cover a typical daily commute on electricity. A PHEV that is never plugged in carries a heavy battery around and behaves like a slightly heavier hybrid. That is why regulators and researchers pay close attention to the "utility factor", the share of distance actually driven on electricity.

Range-extended EV (EREV)

An EREV is a plug-in where the engine never drives the wheels: it is a series hybrid with a large, grid-chargeable battery. It drives like a BEV, and the engine starts only to generate electricity when the battery runs low. Because the engine runs at a few fixed operating points, it can be small and tuned for efficiency rather than response.

Battery electric vehicle (BEV)

A BEV has no engine, fuel tank or exhaust. The AFDC's component list is a good map of the system: a traction battery pack, a power electronics controller (the inverter) that controls motor speed and torque, one or more traction motors, an onboard charger that converts AC from the grid to DC, a DC/DC converter that feeds the 12 V auxiliary system, a charge port, a single-speed or simple transmission, and a thermal system that keeps the battery, motor and electronics in their operating range.

In a BEV the battery is the most expensive, heaviest and most safety-critical part of the vehicle. It is watched over by the battery management system (see our guide to how a BMS works), and it sets the vehicle's range, charging speed and much of its packaging.

In India most BEVs on the road are two- and three-wheelers. Their packs are small (a few kWh) and often swappable, and they run at lower voltages than cars, but they face the same engineering questions of cell choice, thermal design and safety.

Fuel cell electric vehicle (FCEV)

An FCEV is also driven only by an electric motor, but it generates electricity on board in a fuel cell stack, where hydrogen and oxygen from the air combine to produce electricity, heat and water. The AFDC explains a useful design point: the amount of energy on board is set by the size of the hydrogen tank, while the power comes from the motor, fuel cell and battery together. That separates power from energy, which a BEV cannot do. The small battery recovers braking energy and covers short bursts of power so the stack can run smoothly.

FCEVs refuel in minutes and suit long-range, heavily used vehicles such as buses and trucks. The constraints are hydrogen production, storage at high pressure and the small number of refuelling stations. In India, a draft amendment to the Central Motor Vehicles Rules published by MoRTH in March 2026 (G.S.R. 202(E)) points type approval of hydrogen fuel cell vehicles in categories M and N to AIS-157, and hydrogen fuel quality to ISO 14687.

Worked example: what one type costs to run versus another

Energy cost per kilometre is where the types differ most for the owner, and it is easy to estimate. The numbers below are illustrative assumptions, not test results. Prices vary by state and over time, so substitute your own:

• Petrol at ₹100 per litre; home electricity at ₹8 per kWh.
• Petrol car: 15 km per litre in mixed driving. Full hybrid: 22 km per litre.
• BEV car: 150 Wh per km measured at the wall socket, including charging losses.

Vehicle	Energy for 100 km	Cost for 100 km
Petrol car	100 / 15 = 6.7 L	≈ ₹667
Full hybrid	100 / 22 = 4.5 L	≈ ₹455
PHEV, 60 km on battery + 40 km as a hybrid	60 × 0.17 = 10.2 kWh + 40 / 20 = 2 L	≈ ₹82 + ₹200 = ₹282
BEV	100 × 0.15 = 15 kWh	≈ ₹120

(The PHEV line assumes 170 Wh per km in electric mode, since it carries an engine as well, and 20 km per litre once in hybrid mode.)

Charging time is the other number engineers get asked about. A 40 kWh pack charged from 10% to 100% on a 7.2 kW AC wall box needs about 36 kWh. With roughly 90% charging efficiency, that is 36 / (7.2 × 0.9) ≈ 5.6 hours, which is fine overnight. On a DC fast charger, going from 10% to 80% adds 28 kWh; if the car averages 45 kW over that window, it takes about 37 minutes. Charging slows above roughly 80% because the BMS limits current as cells approach full voltage, which is why fast-charging figures are usually quoted to 80%.

What each type means for engineers

Type	Where the engineering effort goes
MHEV	Belt starter-generator, 48 V battery and DC/DC converter, start-stop and torque-assist calibration
HEV	Hybrid architecture and transmission, motor-generators, energy management strategy, high-voltage safety
PHEV / EREV	Everything in an HEV plus onboard charger, larger pack, charge-depleting control, battery thermal management
BEV	Cells and pack design, BMS, inverter and motor, thermal system, charging (AC and DC), crash safety of the pack
FCEV	Fuel cell stack and its air, hydrogen and cooling loops, high-pressure hydrogen storage, DC/DC conversion, hybrid control with the buffer battery

The skills overlap heavily. Motor control, power electronics, battery modelling and vehicle-level simulation in MATLAB/Simulink are used across every type, which is why the same engineers often move between hybrid and BEV programmes.

Electric vehicles in India: rules and incentives

Two things shape the Indian market for engineers: type-approval standards and demand incentives.

Standards. Vehicles are type-approved under the Central Motor Vehicles Rules against Automotive Industry Standards (AIS). The ones you will meet in EV and hybrid work include:

• AIS-102 (Part 1): CMVR type approval for hybrid electric vehicles.
• AIS-156: safety requirements for L-category (two- and three-wheeler) electric powertrains, including the traction battery, tightened after battery fires in 2022.
• AIS-038 (Rev. 2): the equivalent requirements for M and N category (cars, buses and trucks) electric powertrains.
• AIS-138: conductive charging systems for electric vehicles (Part 1, AC charging, and Part 2, DC charging).
• AIS-157: hydrogen fuel cell vehicles.

Incentives. The main central scheme is PM E-DRIVE, launched in September 2024. According to the Press Information Bureau factsheet of 1 October 2026, it has an outlay of ₹11,900 crore and has been extended to 31 March 2028. It covers electric two-wheelers, three-wheelers (including e-rickshaws and e-carts), e-ambulances, e-trucks and e-buses, plus public charging and testing agencies. Registered e-2Ws get ₹2,500 per kWh of battery, capped at ₹5,000 per vehicle and limited to vehicles priced up to ₹1.5 lakh ex-factory. The factsheet reports 26.59 lakh EVs sold under the scheme as of June 2026. Hybrids and private electric cars are not among the covered categories, which is one reason India's EV story is led by two- and three-wheelers.

So which type is best?

There is no single answer; it depends on the duty cycle.

• Predictable daily distance and home or workplace charging: a BEV has the lowest running cost and the simplest drivetrain.
• Long, irregular trips with little charging access: a full hybrid gives a large fuel saving with no change in habits.
• Mostly short trips but occasional long ones: a PHEV or EREV works well, but only if it is actually plugged in.
• Heavy vehicles that run all day and must refuel fast: fuel cells are being trialled for exactly this case.

For an engineer, the more useful question is which system you want to work on. The EV Fundamentals course covers the common building blocks. Hybrid control is covered in Introduction to Hybrid Electric Vehicle using MATLAB and Simulink and the PG Program in Hybrid Electric Vehicle Design and Analysis. Full BEV system design is covered in the PG Program in Electric Vehicle Design and Development, and fuel cells in Fuel Cell and Ultracapacitor for EV using MATLAB and Simulink.

Frequently asked questions

Is a hybrid an electric vehicle?

Partly. Hybrids are "electrified" vehicles because an electric motor helps drive them, but all of their energy comes from fuel. When people say "EV" without qualification, they usually mean a battery electric vehicle.

Do hybrid cars need to be charged?

Mild and full hybrids do not, and cannot, be plugged in. Their battery is charged by the engine and by regenerative braking. Only plug-in hybrids and range-extended EVs have a charge port.

What is the difference between a mild hybrid and a full hybrid?

A mild hybrid's motor only assists the engine and enables smooth start-stop; it cannot move the car on electricity alone. A full hybrid has a bigger battery and motor and can drive short distances at low speed on electricity.

What is the difference between a PHEV and an EREV?

In a PHEV both the engine and the motor can drive the wheels. In an EREV only the motor drives the wheels, and the engine acts purely as a generator when the battery runs low.

Which type of EV is most common in India?

Battery electric two- and three-wheelers, by a wide margin. They are also the main focus of central incentives such as PM E-DRIVE.

Are fuel cell cars available in India?

Not as a mass-market product. Fuel cell technology is being trialled mainly for buses and trucks, and the rules for type approval of hydrogen vehicles are being put in place.

Sources and further reading

• U.S. Department of Energy, Alternative Fuels Data Center: Hybrid Electric Vehicles, How do plug-in hybrid electric cars work?, How do all-electric cars work?, How do fuel cell electric vehicles work?
• SAE International, J1715: Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV) Terminology
• Press Information Bureau, PM E-DRIVE Scheme factsheet (1 October 2026)
• Ministry of Road Transport and Highways, Draft Central Motor Vehicles Rules amendment on hydrogen vehicles, G.S.R. 202(E) (20 March 2026)
• ARAI, AIS-138 Part 1: Electric vehicle conductive AC charging system
• Toyota Kirloskar Motor, Innova Hycross specifications