In Europe, Prepare to Switch Gears : Auto rental: Price and size vary widely, and in all but the most expensive categories, expect a stick-shift.

Travelers interested in renting a car in Europe have many options to consider. Price is usually the major issue, but there are also the factors of comfort, luggage space, security, automatic or manual transmission and, possibly, geographic restrictions on how far you can drive the car. It can get confusing at times, what with all the possibilities.

There are a variety of car groups from which to choose, generally ranging from the least-expensive two-door subcompacts to pricier four-door luxury cars. Other standard categories are station wagons, sports cars and mini-buses. Each category may have a number of options, with the chief differences among vehicles being the amount of passenger and baggage space, in addition to price.

Among the car rental companies that do business in Europe are such familiar names as Avis, Budget, Hertz and Thrifty. Eurodollar and Europcar are European-based companies represented in the United States by Dollar and National, respectively. In addition, there are a number of U.S.-based wholesalers who arrange rentals through a variety of European companies. These wholesalers include Kemwel, Auto Europe, Connex, Europe by Car, Foremost Euro-Car and Holiday Autos.

One advantage of dealing with a company that has operations in several countries becomes clear when problems arise, such as the need for roadside service or when a car needs to be replaced.

“We only book car rentals with companies that operate in more than one European country, but we book equally between multinational companies (such as Avis, Budget, Hertz and Thrifty) and U.S.-based wholesalers, and we haven’t had any major complaints about one or the other,” said Martha Scott, co-owner of Glendale Travel. “Consumers should find out in advance if the company in Europe is a multi-country operation or not.”

Representative of most companies that rent cars in Europe is the system used by Kemwel. Within the popular two-door category, Kemwel has three separate groups, starting with the smallest models, such as a Fiat Panda and Austin Metro, that seat two to three people and hold two to three standard-size suitcases.

The next option would be slightly larger autos, such as the Ford Fiesta and Opel Corso, seating three to four passengers and providing a little more luggage capacity. The third option, two-door cars such as Ford Escorts and Volkswagen Golfs, seat four people with greater ease and offer still more baggage space.

With four-door cars, there are again three variations. The first option, using such autos as an Opel Kadett and Ford Orion, has room for four to five people and holds four to five suitcases. For more room, travelers can move up to the next category, which might include a Ford Sierra or Opel Vectra. Even more comfort comes with the third group, one that includes such vehicles as the Mercedes-Benz 190 and Renault 25.

However, multinational car rental companies may offer even more selections, further complicating the selection process. For example, Hertz offers as many as 12 car groups in some countries. Its roster might include a “mini” group, with cars for one or two passengers with limited luggage space; an economy group, for two people with two medium-sized suitcases; a compact group, for two to four people and more luggage space; intermediate and standard groups, for four to five passengers; a full-size group, featuring cars that can hold five passengers comfortably; premium and luxury groups (which are only available in major cities downtown and at the airports), and a “prestige” group (available only in capitals). Rounding out the possible choices could be sports cars/convertibles, station wagons and mini-buses.

Cars in the various categories can also vary from company to company, and from country to country. One rental car company could, conceivably, list the same car in different groups in different countries. It’s also possible that, while the categories remain constant from country to country, the types of cars available will vary.

Miscalculating the amount of room their luggage will require is one of the biggest mistakes travelers make when renting cars in Europe.

Many rental cars are hatchback models, which lack separate trunk areas, so consumers shouldn’t automatically assume that they will have a lockable trunk. When the rear of a hatchback is filled to capacity, leftover baggage has to go in the seating area. With more luggage visible, security can then become a problem.

The length of the driving trip is also a key factor. The longer the journey, the more important is comfort. Purchases made along the way can also lead to more cramped driving conditions.

Some travelers, faced with the last-minute discovery that a larger car is necessary, may need to dip into their budget to pay for a bigger vehicle. But there’s no guarantee that a larger car, within the traveler’s budget range, will be available. Moreover, car rental companies often offer a lower price if the vehicle is booked in the United States.

“If you have to re-book in Europe, the price of the car can be as much as 50% higher than if the same category were booked in the U.S.,” Harrison warned.

Another decision for some travelers may be whether to ask for an automatic or manual transmission car.

Automatic transmission, when available, is more expensive. Based on its rates in 1992, Avis estimated about a 35% difference in cost between a manual car in category A, its least expensive category, and a car in category D, the first category offering cars with automatic transmission.

Using Hertz’s 1992 prices, and its least-expensive mini group, a manual transmission car rented for seven days would cost $172 in Germany, $222 in France and $187 in the United Kingdom. The least-expensive car with an automatic transmission would cost $305 in Germany, $375 in France (plus a 78-cent charge per kilometer) and $254 in the United Kingdom.

Two other factors for travelers to consider when renting a car in Europe: Air conditioning only comes with the more expensive cars, and the value-added tax, which ranges from 10%-25%, depending on the country, may not be included in the price of the rental.

Among the car rental companies handling rentals in Europe are: Auto Europe, (800) 223-5555; Avis, (800) 331-1084; Budget, (800) 472- 3325; Connex, (800) 333-3949; Dollar, (800) 800-6000; Europe by Car, (800) 252-9401; Foremost Euro-Car, (800) 272- 3299; Hertz, (800) 654-3001; Holiday Autos, (800) 422-7737; Kemwel, (800) 678-0678; National, (800) 227-3876; Renault Eurodrive, (800) 477-7116, and Thrifty, (800) 331-9111.