With an ever-growing landscape of plug-in electric vehicles, there is now more potential than ever for confusion among potential buyers.
To the casual observer, the umbrella term “electric car” can mean anything from an all-electric vehicle to even a hybrid.
For drivers of fully electric cars with no tailpipes, this can sound like blasphemy.
To make things more confusing, some models are offered in several variations.
For example, the BMW i3 is offered as both a pure electric car and as an electric car with a backup gasoline engine.
And the Toyota Prius can be bought either as a regular hybrid or (in certain regions) the far less-common plug-in hybrid version.
2014 BMW i3 (German-market version), Amsterdam, Oct 2013
There are three primary types of vehicles that plug into the wall to recharge on-board battery packs that let them drive some or all of their miles on electric power.
Here's our brief primer on the major differences among vehicles that use electric motors to power their wheels--including conventional hybrids, which don't plug in.
First is the most commonly thought-of "electric car," also known as a battery-electric vehicle (abbreviated BEV). These cars run only on a battery, and cannot use gasoline at all.
This type of electric car has no engine: Its battery provides power directly to the electric motor that turns the wheels, which converts that energy to torque with roughly 90-percent efficiency.
2011 Nissan Leaf - battery pack cutaway
(In gasoline-powered cars, a combustion engine converts the chemical energy in the gasoline into mechanical energy, or motion, in the crankshaft with about 25 percent efficiency.)
Battery-electric vehicles have excellent torque, never need an oil change, and have by far the least moving parts, so they are simple to maintain.
They're cheap to run--generally one-fifth to one-third the cost per mile of a 25-mpg gasoline car--but today, most have a range of less than 100 miles.
2015 Tesla Model S 70D, Apr 2015 [photo: David Noland]
The exception is the Tesla Model S which is now rated at 240 to 270 265 miles.
It can also quick-charge at the growing network of Tesla Superchargers, which recharge the battery faster than that of any other electric vehicle.
One of the greatest benefits of electric cars is that it's possible to recharge them entirely on alternative energy. Many electric car owners charge their cars using power from solar panels on their houses.
Examples of battery-electric vehicles include the Nissan Leaf--the highest-volume electric car ever built--along with the Tesla Model S, the BMW i3, and a slew of lower-volume offerings.
2015 Nissan Leaf
Cars from second group that are currently on sale include the Chevrolet Spark EV, Fiat 500e, Ford Focus Electric, Kia Soul EV, Mercedes-Benz B-Class Electric Drive, Mitsubishi i-MiEV, Smart ForTwo Electric Drive, and Volkswagen e-Golf.
Every other plug-in car uses at least some gasoline, though often far less than regular cars.
Range-Extended Electric Cars: always powered by an electric motor
The second category of electric car is the range-extended electric vehicle (REEV or REx), alternatively known as an extended-range electric vehicle (EREV).
These cars run solely on the energy from their batteries until the charge gets low.
2014 BMW i3 REx vs Chevrolet Volt comparison [photos: David Noland, Tom Moloughney]
Then, and only then, a gasoline engine switches on--not to power the wheels, but only to recharge the battery--while the driver continues on her merry way.
Current range-extended models allow the driver to travel 35 to 90 miles using only electricity, before the gas engine extends the range.
Range-extended electric cars can be recharged at home or at local charging stations; they can also be filled with gasoline.
Their benefit is that you drive all-electric for most of your daily travels, but can use gasoline when you need to go a bit further--or go on a longer road trip.
Many drivers run their range-extended electric cars on electricity so much of the time that they have astronomical values for their blended "gas mileage."
For example, they might only switch on the gasoline engine once or twice a month--covering hundreds of miles on no gasoline at all.
2009 Fisker Karma prototype
While these vehicles can be driven only on electricity much of the time, they will still need the occasional oil change and other maintenance on their engines.
But they provide flexibility that most battery-only cars can’t offer, eliminating "range anxiety" on the part of drivers.
Range-extended electric vehicles on the market today include the BMW i3 REx, the Cadillac ELR luxury sport coupe, and the 2015 Chevrolet Volt.
(The Volt and ELR come with an asterisk--sometimes their engines help to drive the wheels--but that's not worth going into here. Trust us.)
2012 Toyota Prius Plug-In Hybrid, production version road test, San Diego, CA, Jan 2012
Plug-In Hybrids: mixing gas and electric power
A plug-in hybrid electric vehicle (PHEV) is a variation of conventional hybrid-electric cars, with a larger battery pack that can be plugged into the wall to recharge.
Plug-in hybrids often have more powerful electric motors than the conventional hybrids they're derived from, meaning they spend more time in electric-only mode.
Still, while they have rated electric ranges of 6 to perhaps 21 miles, they will all switch on their engines when pushed hard.
Paradoxically, the best-selling plug-in hybrid model has the lowest electric range of any plug-in vehicle sold in the U.S.
2012 Toyota Prius Plug-In Hybrid, production version road test, San Diego, CA, Jan 2012
The plug-in version of the well-known Toyota Prius hybrid can travel only 6 miles continuously on electric power, according to EPA tests, and has a total electric range of just 11 miles.
Plug-in hybrid models from Ford, Honda, and Hyundai can go further: up to 20 miles or so.
But they still have to use the gasoline engine when the driver accelerates hard, even if there's charge remaining in their batteries.
That's what makes them different from range-extended electric cars (above), which never turn on the engine if there's battery range left.
And that makes for a different driving experience: In electric mode, plug-in hybrids still turn the engine on and off occasionally--depending how you drive and at what speeds--while range-extended electrics never do.
2016 Chevrolet Volt
It may not sound like much, but experienced electric drivers will say the absence of any noise and vibration from a combustion engine makes a huge difference to driving calm.
Plug-in hybrids too still need oil changes and regular engine and transmission maintenance, but they can provide excellent gas mileage to owners with shorter commutes.
Examples of plug-in hybrids on sale today include the Ford C-Max Energi and Fusion Energi, the Honda Accord Plug-In Hybrid, and Toyota Prius Plug-In Hybrid, and soon the 2016 Chevrolet Volt.
Hybrid Cars: NOT electric (but "electrified")
A hybrid is not an electric car. They're often lumped together with cars that plug in, frequently by journalists--but conventional hybrids cannot be plugged in.
The only way to charge their battery packs is by using motion produced by running their gasoline engines.
2015 Toyota Prius Liftback
Hybrids can often power themselves on electricity alone, for distances of up to a mile or so at lower speeds and under lighter loads, which is why they're often referred to as "electrified" cars.
But, the battery energy that powers a hybrid has been recaptured through regenerative braking or engine overrun--not from the electric grid.
They generally do not share the benefits of all-electric cars, including strong electric-only acceleration, far less maintenance, and the ability to cut fossil-fuel use to zero when recharging with solar energy.
Hybrids do provide better fuel efficiency than gasoline-only vehicles; the Toyota Prius has been rated at 50 mpg combined since its 2010 launch, and no other vehicle has surpassed that rating.
2000 Honda Insight
And hybrids have reduced gasoline use in the U.S. since 2000.
But in terms of overall efficiency--how many miles you can travel on a given amount of energy--electric vehicles leave hybrids in the dust. In terms of energy use, plugging in is simply superior to gassing up.
Today's hybrids are offered in many more vehicle segments: not only smaller sedans and hatchbacks but also SUVs. Most automakers now have at least one hybrid in their lineup.
Toyota dominates the world's hybrid market, with more than 5 million sold and more than two dozen different hybrid models currently on sale globally.
2016 Toyota RAV4 Hybrid
Hybrids on sale today include the one that started it all--the Toyota Prius--along with hybrid models of many other cars. Those include several mid-size sedans with hybrid variants: the Ford Fusion, Honda Accord, Hyundai Sonata, Kia Optima, and Toyota Camry.
As of this year, Toyota has also added a RAV4 Hybrid compact crossover utility vehicle to its longstanding Highlander Hybrid mid-size SUV.
And Toyota's luxury brand Lexus has also long offered a hybrid model of its RX crossover utility vehicle.