Plan Any Road Trip From Five Numbers
Most of a long drive can be settled before setting off, and five figures cover it.
1. How many days
The road trip planner on 2,400 km at 90 km/h, capped at 8 driving hours a day with 20-minute breaks every 2 hours: 26.67 driving hours, 4 days, 600 km a day, 13 breaks totalling 4.33 hours.
Use a lower average speed than the limit suggests. Door-to-door averages are well below cruising speeds, and the break total is the figure most often left out of a plan.
2. How far between charges or fills
The range calculator on 75 kWh at 18 kWh/100 km gives 416.7 km full, and 333.3 km at 80% state of charge. Plan arrivals at 10–20% rather than zero, so the usable leg is shorter than the headline range.
3. How long the stops take
The charging calculator on that battery, 20→80%: 20 minutes at 150 kW, an hour at 50 kW, 6 h 45 at 7.4 kW. Going on to 100% at 150 kW takes 27 minutes rather than 20 — and in reality more, because the charge curve tapers.
Two stops to 80% generally beat one to 100%, and a 20-minute rapid stop lines up neatly with the two-hour break cadence.
4. What it costs
The trip cost calculator on 600 km: petrol at 7 L/100 km and £1.60/L is £67.20; an EV at 18 kWh/100 km and £0.30/kWh is £32.40. The energy price is the input that moves the answer most — rapid charging can be several times a home rate.
5. How much road you need to stop
The one worth carrying rather than computing. At 100 km/h with a 1.5-second reaction: 97.85 m dry, 139.99 m wet. Braking distance quadruples when speed doubles, and reaction time alone spans 50 m between an alert driver and a distracted one.
That figure is the argument for following distance, and it does not change because a vehicle has driver assistance — assistance removes reaction time, not braking distance.
The order to do them in
Days first, because it sets the shape. Then range, because it decides where the stops are. Then charging, because it decides how long they take. Cost last, because it is the one that changes nothing about the plan.
And stopping distance is not a planning number at all — it is the one to have internalised before the trip, so that following distance is a habit rather than a calculation.
What none of it covers
These are planning estimates on flat assumptions: constant speed, constant consumption, a single energy price, idealised braking. Traffic, terrain, weather and closures all move them.
Nothing here is a substitute for your vehicle's own documentation — particularly on driver-assistance limits and on what you remain responsible for — or for the regulations where you are driving.
Write them down before you go
Days and daily distance, usable leg range, charging stop length, the trip's energy cost, and your stopping distance at cruising speed. Five figures on one card.
The point is not precision — it is that none of them are being worked out at a service station with everyone waiting. A plan that exists on paper survives a change of route; one held in your head does not.
Recompute what changes
Range and consumption move seasonally, so a winter trip should be planned with winter figures rather than last summer's. Energy prices move too, and rapid-charging rates in particular can change between trips.
The stopping-distance figure is the only one that never changes, which is why it is the one worth memorising rather than looking up.
For the numbers behind that final figure, the Stopping Distance Reference Table lists total stopping distance at every common speed across four road conditions.