How-to guide
What car hire really costs: the second driver and the mileage cap
Car-hire comparison lists sort by the headline price: the rental, for the dates you typed. Two things that are not in that price change which car is cheapest more often than anything else: a second driver, and a mileage cap on a long drive. Here is what each did to real searches.
Worked examples re-measured every day; this version from a search on 7 October 2026. We earn a commission if you book through our links; it never changes the order of results.
1. Two drivers: the cheapest car that wasn't
Faro Airport
A week at Faro Airport, 23 November 2026 to 30 November 2026, a small car, two drivers. Searched 7 October 2026, 1,491 cars.
| Headline price | Second driver | What you pay | |
|---|---|---|---|
| Cheapest on the list (Peugeot 108) | €17.89 | €70.00 | €87.89 |
| Cheapest with two drivers (Fiat 500) | €30.81 | €21.53 | €52.34 |
Picking the headline-cheapest car would have cost €35.55 more (68% on top of the real cheapest). The cheaper option also held a smaller deposit on the card: €1,070 against €1,599.
Porto Airport
A week at Porto Airport, 23 November 2026 to 30 November 2026, a small car, two drivers. Searched 7 October 2026, 1,505 cars.
| Headline price | Second driver | What you pay | |
|---|---|---|---|
| Cheapest on the list (Fiat Panda) | €12.40 | €70.00 | €82.40 |
| Cheapest with two drivers (Fiat 500) | €20.59 | €0.00 | €20.59 |
Picking the headline-cheapest car would have cost €61.81 more (300% on top of the real cheapest). The cheaper option also held a smaller deposit on the card: €1,400 against €1,650.
The second driver is usually one fee for the whole rental, but it varies by supplier from nothing to €70 and more. At Faro 90% of suppliers charge one. Add it to every quote before you compare, or the "cheapest" car can be the wrong one.
2. A 1,000-mile week from London: miles, not kilometres
London Stansted Airport
A week from London Stansted Airport, 23 November 2026 to 30 November 2026, a small car, about 1,600 km (1,000 miles) of driving. Searched 7 October 2026, 358 cars.
| Headline price | Included | Extra miles | What you pay | |
|---|---|---|---|---|
| Cheapest on the list (Fiat 500) | £86.88 | 100 miles/day | 294 at £0.20/mile = £58.84 | £145.72 |
| Cheapest for this trip (Fiat 500) | £120.58 | Unlimited | none | £120.58 |
The headline-cheapest car would have cost £25.14 more once the extra miles were paid.
London Gatwick Airport
A week from London Gatwick Airport, 23 November 2026 to 30 November 2026, a small car, about 1,600 km (1,000 miles) of driving. Searched 7 October 2026, 464 cars.
| Headline price | Included | Extra miles | What you pay | |
|---|---|---|---|---|
| Cheapest on the list (Fiat 500) | £55.89 | 100 miles/day | 294 at £0.50/mile = £147.11 | £203.00 |
| Cheapest for this trip (Fiat 500) | £62.90 | Unlimited | none | £62.90 |
The headline-cheapest car would have cost £140.10 more once the extra miles were paid.
Three things to check on any offer with a mileage cap:
- The unit. UK allowances are usually in miles. 700 miles is 1,127 km, a lot more than "700".
- Per day or per rental. "100 miles a day" on a week is 700 in total, and most suppliers let you use it unevenly across the days.
- The rate for every mile over. It sits in the supplier's rental conditions, not in the price. We keep the rates we have checked, with their source, and add them to the total when your trip goes over.
Fuel is the other cost that grows with distance. Our search adds it per car for the distance you enter, and on a long trip a small hybrid can change the order again.
How to compare, in one line
Put your trip into the price before you compare: the number of drivers, the distance, the hours you collect and return the car, and the card you will pay the deposit with. That is what our search does for every car on the list.
Price your own trip
Second driver, distance and desk hours included, for every car.
Figures are single dated searches and move daily; always check the offer you book. More: renting a car at Faro: 12 tips · all guides · how we measure.