Can driving slower in an EV get you there sooner?

Yes, and it happens more often than people expect. Range falls smoothly as speed rises, but charging stops arrive in whole steps: you either need one or you do not. Whenever a higher cruising speed pushes the trip over the edge of a step, you pay a full stop of perhaps 25 minutes to save a handful of minutes of driving. On a 200 mile trip in a car with 250 miles of rated range, holding 70 mph can finish the trip without stopping while 80 mph needs a stop, and the slower run arrives first.

How does the calculator estimate range at a given speed?

Energy per mile is modelled as an aerodynamic part that rises with the square of speed plus a roughly constant part covering rolling resistance and accessories. Range at your chosen speed is your reference range divided by that ratio. The split between the two parts is set by body type, because a taller, blunter vehicle spends more of its energy pushing air aside. The shape was fitted to published fleet data covering an electric sedan and an electric van, and it reproduces the measured range at 50, 60, 70 and 80 mph to within about one percent.

Why does the calculator charge to 80 percent rather than 100?

Because charging slows markedly as the battery fills. The last portion of a top-up can take as long as the first two thirds, so on a road trip it is usually faster to stop again briefly than to sit waiting for the final twenty percent. The charge-to figure is adjustable, and raising it will reduce the number of stops while making each one longer, which is exactly the trade the tool is there to show.

What should I use for the stop time?

Use door to door, not the time the car is drawing current. Leaving the motorway, finding the charger, plugging in, waiting, unplugging and rejoining typically adds ten minutes or more to whatever the charging curve costs. Twenty-five minutes is a reasonable default for a fast charger on a well-served route. If your route relies on slower chargers or awkward detours, raise it, and the crossover speed will drop.

Why is my real range lower than the rated figure?

A rated range comes from a mixed test cycle that includes a lot of low-speed driving, which is where an electric car is at its most efficient. Sustained motorway speed is its weakest case, so a road trip sits well below the sticker. Cold weather adds a second, separate penalty through cabin heating and battery conditioning. Entering your own observed range at a known steady speed, rather than the rated figure, makes every result on this page more accurate.

EV road trip planner

EV charging stop calculator

Range falls on a curve. Charging stops arrive in whole steps. Find the cruising speed that actually gets you there soonest.

Range at this speed —

Charging stops —

Total time —

Every speed compared

Same trip, same car, different cruising speeds. The fastest arrival is highlighted.

Why a slower speed can win

Two things are happening at once, and they have different shapes.

Range falls smoothly. Aerodynamic drag rises with the square of speed, so every extra mile per hour costs a little more range than the one before it. Measured fleet data puts an electric sedan at 226 miles at 70 mph and 200 at 80.

Charging arrives in steps. You either need a stop or you do not. There is no half a stop. So the moment a higher speed pushes the trip past the edge of a step, you pay the full price of one, typically twenty-five minutes door to door, to buy back a handful of minutes of driving.

That is the whole mechanism. Near a step edge, slowing down wins. Well away from one, speed wins as you would expect. The table above shows where the edges fall for your particular trip, which is not something intuition handles well.

What the model assumes

Energy per mile is treated as an aerodynamic part that scales with the square of speed plus a roughly constant part for rolling resistance and accessories. Body type sets the split between them, because a taller, blunter vehicle spends more of its energy on air. The curve was fitted to published fleet figures for an electric sedan and an electric van and reproduces their measured range at 50, 60, 70 and 80 mph to within about one percent.

It assumes flat ground, mild weather, no towing and a charger where you need one. Cold weather is a separate penalty this tool does not model, and it is a large one. Elevation and headwind are not modelled either.

The single biggest improvement you can make to the accuracy is to replace the rated range with your own observed range at a known steady speed, and set the reference speed to match. A rated figure comes from a mixed cycle containing a lot of low-speed driving, which is where an EV looks best and a road trip looks nothing like.

Measuring it needs an honest distance. A car odometer counts wheel rotations against a stored tyre circumference and typically reads 1 to 3 percent high, as we cover in is your odometer accurate, which quietly inflates any range or efficiency figure you calculate from it. The GPS odometer measures distance independently of the car.

EV range vs speed — the fleet data and the physics behind this tool
MPGe to kWh/100mi converter — five EV efficiency units
80 vs 70 in a petrol car — where the cost is money instead of time
Driving time by distance — the simple version, no charging
Live GPS speedometer — hold a steady speed accurately

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Every speed compared

Why a slower speed can win

What the model assumes

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