Budget a family road trip including fuel and stops.
Fuel is the line people estimate and the one that matters least. Distance divided by a hundred, times consumption, gives litres; times price gives the fuel bill — and for a typical family trip that is under a third of the budget. Accommodation and food dominate, and food is counted across nights plus one because you eat on both the outbound and return days. The per-traveller figure is what makes a road trip comparable against flying, where fuel scales per person rather than per vehicle.
Family road trip budget
Fuel = distance / 100 x L/100km x price per litre; total = fuel + nights x accommodation + (nights + 1) x daily food
For a true cost, yes — depreciation, tyres and servicing add roughly the same again as fuel per kilometre on many vehicles. This budget covers out-of-pocket trip spending, which is what most people plan against.
Enter consumption in kWh/100km and the price per kWh in place of litres, and the arithmetic is unchanged. Home charging typically cuts the energy line by half or more against petrol; motorway rapid charging often does not.
Because fuel and accommodation are shared across the vehicle while air fares are charged per seat. The per-traveller figure crosses below a typical fare somewhere around three occupants.