Picking a car up at one end of a coast and leaving it at the other attracts a fee that can rival the rental itself. The charge reflects a real logistical cost.
Fleets have to be balanced
A rental branch needs cars available where customers want to collect them. Every one-way rental moves a vehicle from a location that needed it to one that may not.
If the flow ran evenly in both directions the problem would solve itself, but on tourist routes it rarely does. Traffic moves predominantly one way through a season.
The company therefore ends the summer with vehicles piled at one end of the coast and shortages at the other, and correcting that costs money.
Repositioning is a manual operation
Returning a car to its home branch means paying someone to drive it, covering fuel, tolls and their return journey, or loading several vehicles onto a transporter.
On a coastal route both options are slow, because the roads that make the drive attractive are the same roads that make repositioning inefficient.
The drop fee is an attempt to recover that cost in advance rather than absorb it at the end of the season.
The fee is not uniform
Charges differ enormously by direction, by distance and by whether the two locations sit within the same operating region.
Drops between major airports in the same country are often modest or waived, because the network already runs vehicles between them and the imbalance is manageable.
Drops into small coastal towns, onto islands or across a border are where the figures become severe, since none of those places generates enough outbound demand to rebalance itself.
Seasonality moves the number
Where the seasonal flow runs against the tourist tide, the fee can fall to nothing. A company that needs cars moved in a particular direction is happy for a customer to do it.
The same route quoted in the opposite direction, or at a different point in the year, can carry a substantial charge. Both prices are correct.
Checking the reverse itinerary before booking sometimes reveals that running the coast the other way costs materially less for an identical trip.
What this means for planning a linear route
Loop itineraries avoid the fee entirely, and on a coast with a decent inland return road the loop is often the better drive anyway.
Where a linear route is the point, combining a one-way rental with a train or ferry back to the start can cost less than the drop charge alone.
The comparison is worth doing before the accommodation is booked, because the shape of the itinerary is far easier to change at that stage than afterwards.