range

Range is usually printed as a number. It is measured on a test cycle, rounded, and put in a brochure. The driver never meets that number. They meet a road, a temperature, a load, a headwind, and a charger that may or may not be working when they arrive.

So the first sense of range belongs to the car, and the second belongs to the journey. The first can be engineered. The second has to be earned, on every trip, with information the driver can trust.

A route that ends with twelve per cent left is a promise. A route that ends with twelve per cent, give or take five, is a forecast. Drivers forgive a forecast that was wrong in the way it said it might be. They do not forgive a promise.¹

The band matters more than the line. It tells the driver where the margin is, and it tells the planner where to put the stop.

Every car shows a range estimate, and every driver learns to distrust it within a week. It is not wrong so much as alone: it knows the battery and nothing about the road ahead. Put it next to the route and it becomes useful again.

The interesting work is not a better number. It is giving the number company: the grid it will charge from, the queue it may meet, the tariff it will pay.