The criteria worth comparing, the three kinds of supplier, and the one most travellers get wrong.

Alpine lakes, a high pass, wine country, caves and the Adriatic — in one direction, without doubling back.

The four things that catch visitors out: the vignette, winter equipment, headlights and the mountain passes.

Desk locations, how long to budget, what to have ready, and how to handle the counter upsell.

Nine adjustments that move the final number most, in rough order of how much they save.

Where to rent, driving rules, tolls, insurance, car size and the mistakes worth avoiding.