Vehicle size classes commonly used in the USA categorize automobiles by their relative lengths and volumes.  To them belong micro cars, subcompact cars, compact cars, mid size and full size cars.  In Europe car classes are determined as A-class, B-class, C-class, C/D-class and large cars; yet, the performance characteristics when defining the size class are the same as in the USA.  

A micro car is an extremely small automobile.  There are various definitions for micro cars, such as: 'less than 3 meters in length' , or 'less than 2400 litres interior volume'.  Typically, micro cars seat only the driver and a single passenger, and many of them have only three wheels.  Micro cars are usually designed and produced for economic purposes when materials and heavy equipment are scarce or fuel is scarce and expensive.  Micro cars design flourished after World War II in Europe because post-war Europe lacked gasoline.  Such transport facilities use much less fuel than the more common size cars do.

Next come subcompact cars.  A subcompact car is smaller than a compact car, but larger than a micro car.  Vehicles of the sort usually have four or more seats (compared to micro cars with their two-person sitting) and a wheelbase of 2.54 meters or less or between 2400 L and 2800 L of interior volume.  Still, a popular usage of this term frequently ignores these boundaries.  Subcompact cars are commonly sold in Europe and Japan where they enjoy huge popularity; they are also fairly popular in North America.

Compact cars are automobiles smaller than mid size cars, but larger than subcompact cars.  They usually have wheelbase between 2.54 meters and 2.67 meters.  And interior volumes for those cars are 2800 L and 3000 L.  First compact cars were made in the United States in 1959 and 1960, when the Rambler American, Studebaker Lark, Chevrolet Corvair, Ford Falcon, and Plymouth Valiant all appeared in rapid succession.  Today, although the general downsizing of all vehicles has somewhat blurred size class distinctions, the compact segment is still discernible as a class smaller than the average car but larger than the smallest models on the market.  Yet, compact cars are not commonly used in Europe, where vehicles tend to be smaller.

Mid size cars are middle cars.  This is an American term for an automobile with a size between a compact and a full size or a standard size car.  In Europe, cars of a similar size are often considered to be family or large family vehicles.  Mid size cars today usually have wheelbase between 2.68 meters and 2.79 meters with an interior volume between 3000 L and 3300 L.  Those are the most popular size cars sold in the United States. Well-known examples include the Toyota Camry and Honda Accord.  There is still a trend for domestic entries to be larger than the imports, however, such as the Ford Taurus, which has competed well with these models because of its larger size in every dimension.

A full size car is the term used in North America for a car larger than a mid size car with a wheelbase greater than 2.79 meters and greater than 3300 L of interior volume.  Sales of full size cars in North America have been declining since the 1970s because of fuel prices rise.  A well-known example of a full size car is the Ford Crown Victoria.  In Europe, a full size car is considered to be a luxury or exotic vehicle. Among full size car examples are globally known Audi A8, BMW 7-Series, Mercedes-Benz S-Class and Jaguar XJ.

Here are the main performance features to be taken into account when renting or buying a vehicle.  As you can see, all the classes described are designed to meet the requirements of a certain objective client: micro cars are usually aimed at trendy audience, predominantly women, yet inconvenient when traveling in the family circle; mid size cars would be suitable for a group journey; a full size car is usually preferred by a well-off society level.  Choose the one that is to satisfy all your needs.