(dinging)

(upbeat music)

[Narrator] Starting a hybrid car

is as easy as pushing a button.

But what's inside is anything but simple.

In the rear of the car,

beneath the fast food wrappers and other junk in your trunk,

is a roughly 100-pound, rechargeable battery pack.

Comprised of many smaller, nickel metal hydride,

or lithium ion batteries,

similar to those in your cell phones.

Current from the battery is directed to the electric motor,

which contains around a kilogram of neodymium,

a rare earth metal used to make the world's strongest

commercially-available permanent magnets.

The motor can produce high torque at low RPMs.

It isn't enough to reveal a Higgs Boson particle,

but it can generate around 80 horsepower.

At around 40 miles per hour

the internal combustion engine kicks in

providing additional power,

and extending the hybrid's range

to hundreds of miles without refueling.

Internal combustion engines run on good ole gasoline,

which packs nearly 10 times more energy than TNT.

But, they also release carbon dioxide, benzene,

and other fun toxins into the atmosphere.

The hybrid's special sauce,

is a software-guided drive train with planetary gears

that finds the optimal balance of power

between the gas engine and the electric motor,

engaging both when the driver needs to go all Formula One.

(tires screeching)

It all comes full circle when you hit the brakes.

The car's kinetic energy goes into rotating the motor,

which effectively becomes a generator.

This not only slows the vehicle,

but also produces electricity to recharge the battery.

It's called regenerative braking,

and is perhaps the only known benefit

of stop and go traffic,

other than getting to listen to all of your Wired podcasts.

(car horns honking)

Enjoy other episodes of What's Inside

by subscribing to the Wired channel.