Is buying an EV a good idea, if most of my driving is done on country roads and highways?

You’re spot on in that an EV’s `economy’ is the reverse of a conventional car. Because it has no transmission to vary the gear ratios, running an EV at highway speeds requires the motor to spin faster. And that means more electricity is consumed. But the main factor in this difference is that an EV can regenerate power that would normally be lost in slowing or braking in a conventional car.

When the driver of a normal car hits the brakes, the car slows, with the excess energy being lost as heat and noise via the brakes. But in an EV, the initial slowing process doesn’t involve the brakes at all. Instead, the electric motor is electrically flipped to become a generator and the physical drag from that is what slows the car, the generator making power in the process which is fed back into the batteries. Only when the driver leans harder on the brake pedal in an EV do the actual brake pads come into play.

So, for an EV to make free power in that way relies on the driver slowing down. Which, of course, on the freeway might not happen for hours. But in stop-start traffic, the car is always changing speed and whenever that change is a drop in speed or the car is coasting down a hill, the car is making power. EV owners who live on a hill often have more energy in the batteries than they left home with in the first part of their journey. It’s probably the EV’s (and the hybrid’s) neatest trick.

It's also why highway running makes an EV less beneficial than city and suburban work. With that in mind, you won’t be wasting your money buying an EV to drive on country roads, but you won’t be taking best advantage of its technology.