Car rental companies operate by purchasing or leasing a number of fleet vehicles and renting them to their customers for a fee. Rental fleets can be structured in several ways – they can be owned outright (these are known as ‘risk vehicles’ because the car rental operator is taking a risk on how much the vehicle will be sold for when it is removed from service), they can be leased, or they can be owned under a guaranteed buy-back program arranged directly through a manufacturer or manufacturer’s financial arm (these are known as ‘repurchase vehicles’ because the manufacturer outlines the exact price of original sale and of repurchase at the end of a defined term).
In the UK, the registration of rental cars can be concealed by using unfamiliar initials or subsidiaries, which can increase the resale value via manufacturer or third-party dealers. In North America, it is common to see rental companies with their own branded second-hand car dealers where the ex-rental stock is sold directly to the public. Alternatively, auctions are often used in the United States and with the advent of digital platforms, rental cars have increasingly sold the vehicles directly to new and used car dealers bypassing the auction channels.
Most car rental offices offer a range of vehicle sizes to suit a variety of budgets and space requirements and some additionally offer specialized vehicles to suit its location such as convertibles, prestige models, hybrid/electric vehicles, or SUVs and passenger vans. At major airports or in larger cities, some independent car rental agencies offer high-end vehicles for rent. Some specialized companies offer older vehicles at reduced prices.
To allow for a uniform classification and easy comparison of car rental prices, the Association of Car Rental Industry Systems and Standards (ACRISS) has developed the ACRISS Car Classification Code coding system. This describes the size, door count, gearbox type (manual/automatic), and whether the car is air-conditioned, encoded into four letters. The first letter in the Acriss Code represents the general classification of the vehicle (e.g. Mini, Economy, Compact etc.). The second letter specifies the vehicle variant on offer (e.g. 4 Door, Estate, Convertible, SUV etc.). The third letter is generally used to specify the transmission type, although it can also be used to describe how many wheels drive the vehicle, and the fourth letter describes the fuel type and whether the vehicle has air conditioning or not.
Additional classifications based on seat numbers and trunk volume were also set by the Belgian Rent a Car association in order to provide a unified system for assessing the car types in online reservation systems and airline global distribution systems.
Car rentals are subject to many conditions which vary from one country to another and from one company to another. Generally the vehicle must be returned in the same condition it was rented in, and often must not exceed mileage restrictions, otherwise, extra fees may be incurred.
For insurance reasons, some companies stipulate a minimum and/or maximum rental age. In some cases, the minimum age for rental can be as high as 25, even in countries where the minimum legal age to hold a driver's license is much lower, e.g. 14,15,16 or 17 in the United States. It is not uncommon for there to be a young driver surcharge for all drivers aged under 25.
In all cases, a valid driver's license is required in order to rent a vehicle, and some countries require an International Driving Permit (IDP).
The majority of car rental companies require the use of a credit card to charge additional fees should a defect be found with the car on its return or for road tolls, motoring related fines, or missing fuel. In lieu of a credit card, some companies require a large cash deposit. Some companies permit a debit card for deposits, typically with proof of a round-trip travel ticket, e.g. an airline, bus, or train ticket.