Routing software offers an option to avoid tolls, and it is often assumed to be the economical choice. For longer journeys the arithmetic frequently runs the other way.
Toll-free routes are longer as well as slower
Motorways are built to connect points directly, while the older road network follows terrain and passes through the towns it was built to serve.
The alternative route is therefore usually longer in distance, not merely slower, and the additional kilometres consume fuel that the toll would have saved.
On a long journey the difference in distance alone can approach the toll, before any other cost is considered.
Fuel consumption rises on secondary roads
Steady motorway driving at constant speed in a high gear is close to the most efficient condition a car achieves.
Secondary roads impose constant acceleration and braking through villages, junctions and roundabouts, and each cycle wastes energy that was already spent.
Gradients add to this, since motorways are engineered with gentle inclines while older roads climb whatever the terrain presents.
Time carries real cost on a road trip
An extra two hours of driving is two hours removed from the destination, and on a short trip that is a meaningful share of the holiday.
It also increases driver fatigue, which is a safety matter as much as a comfort one, particularly at the end of a long day.
Where the delay pushes an arrival past a check-in deadline or into darkness, it can create costs that have nothing to do with fuel.
The systems themselves differ by country
Some countries charge by distance travelled between entry and exit, others sell a time-based sticker giving unlimited use, and others charge only on specific structures.
Electronic tags allow passage through dedicated lanes and are usually settled by account, while cash and card lanes may be limited at some junctions.
Requirements and enforcement differ by country and change over time, so the applicable arrangements are worth confirming before crossing a border rather than at the barrier.
Where avoiding tolls genuinely wins
Short hops between nearby towns rarely justify a toll, since the motorway's speed advantage has no distance over which to accumulate.
Journeys where the road itself is the point are a different matter entirely, because the slower route is delivering what the trip was for.
The practical approach is a mixed route, using motorway for the transit sections and secondary roads where the scenery justifies the time.