How Electric Cars Are Built: What's Different Under the Skin

A petrol car needs an engine with hundreds of moving parts, a multi-speed gearbox, a fuel system, an exhaust with catalytic converter, and a cooling system for all of it. An EV replaces almost all of that with three main things: a battery pack, one or more electric motors, and the power electronics that connect them. The result is a drivetrain with a few dozen moving parts instead of a couple of thousand.

The main components

• Battery pack — a large, flat, sealed unit under the floor that stores energy and doubles as a structural part of the chassis. It gives EVs their low centre of gravity.
• Electric motor(s) — compact and powerful, delivering full torque from a standstill. Many EVs use one motor; performance and all-wheel-drive models use two or more.
• Inverter — converts the battery's DC into the AC the motor needs, and back again when braking, so the motor can act as a generator (regenerative braking).
• Onboard charger — turns AC from a home or public AC charger into DC for the battery. DC fast chargers bypass it and feed the battery directly.
• Thermal management — liquid cooling and heating loops that keep the battery, motor and cabin at the right temperature; a heat pump makes winter heating far more efficient.
• Single-speed reduction gear — most EVs need no multi-speed gearbox at all.
• Software — the vehicle control unit and battery management system manage power, efficiency, charging and safety, and can be updated over the air.

How the car is assembled

Most EVs are built on a 'skateboard' platform: the battery, motors, suspension and electronics form a flat base, and the body sits on top. This frees up cabin space (no transmission tunnel, often a front boot) and lets manufacturers build several models on one platform. Body panels are pressed, welded or increasingly cast as single large pieces to save weight and assembly steps; then the painted body is married to the skateboard, and interior, glass and wheels are fitted on the final line.

What this means for owners

Fewer parts means less to go wrong and lower routine maintenance — a big part of why the total cost of owning an EV is often lower despite a higher purchase price.