2015 Nissan Leaf
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.)