It’s interesting about the Chevy Volt.
Uniquely, it carries around its own recharger – so it’s not tied to a corded umbilical like other electric cars. So it isn’t gimped by a much-abbreviated radius of action, like all other electric cars – the best of which can travel maybe 150 or so miles before their batteries conk out and the car must hook up to an electric IV for an extended recharging session.
When the Volt’s battery pack’s charge runs down, fresh current is fed into it as you drive – without having to stop driving.
This is superficially similar to the way hybrid works but also very different.
Unlike hybrids, the Volt is a true electric car. A motor and batteries provide the primary motive power – what makes it go – as opposed to back-up power. There is a small (1.5 liter) gas engine, but it serves almost exclusively as a generator. It comes on as needed to make electricity for the batteries, not torque and horsepower to turn the wheels. In the Volt, electric motors do that.
All the time.
The Volt’s electric motors always propel the car.
In a hybrid, the electric motor and batteries take over when the vehicle isn’t moving – or moving at low speed. Most can only creep along for a couple of miles – and no faster than about 30 MPH – before the gas engine cuts in and takes over to propel the car, just like any other car.
The main source of movement in a hybrid car is the gas engine.
A few (the plug-ins, which have more powerful battery packs) can travel for about 10-15 miles and at higher road speeds on battery power alone, but revert to internal combustion for propulsion when the charge depletes. Also, anything less than eggshell-pressure on the throttle causes the hybrid car’s gas engine to kick on – because the battery pack/motors are too weak to provide adequate acceleration by themselves.
Which makes it difficult to avoid regularly using the gas engine, in other words.
As a result, hybrids use a fair amount of gas. The best of them – the plug-in version of the current (2018) Toyota Prius average in the mid-50s. Most of the others are in the low 40s, high 30s. This is good but not nearly as good as the Volt – which uses so little fuel that owners have to worry about the gas in the tank going stale.
The Chevy can travel 50 miles on electricity only – and without driving it like there’s a Faberge egg under the accelerator pedal. The motors/batteries are designed to be powerful enough to accelerate the car adequately without assistance. And if your trip is less than 50 miles, you can plug the thing in when you get there and burn no gas at all on the return trip.
Owners may go a month or more in between fill-ups. Some go months, plural.