In the automotive classification, "2 + 2" means an arrangement with two front seats (for the driver and passenger) and two small rear seats for children or rare fellow travelers.
Cars with a 2 + 2 layout have only two seats in the rear, in contrast to the more common layout with seats for three passengers. The reason for this lies in the low roof, wide wheel arches and wide center tunnel, which is characteristic of sports cars, through which the transmission passes, due to the front-mounted engine and rear-wheel drive.
The latter reason is most relevant, since the third passenger in the middle would be extremely uncomfortable. There is also a lack of legroom for the rear passengers, especially if it is a convertible, as there is a lot of rear space reserved for folding the roof.
There is no official definition of the "2 + 2" layout, but it is generally accepted that such cars must necessarily have rear seats for only two passengers, instead of three, and, as a rule, there is relatively little rear space even for two, a more sporty character than in ordinary cars (or at least appearance) and the body type "coupe" with two doors.
Many convertibles, targas and hatchbacks fit this definition, but are rarely considered "2 + 2". Some cars were specifically marketed as "2 + 2", usually to distinguish them from two-seater open versions of the same models. The most famous examples are the classic Jaguar E-type coupe 2 + 2, Lotus Elan 2 + 2, Nissan 300ZX 2 + 2, Chevrolet Monza 2 + 2, 1965-66 Mustang 2 + 2 and some Pontiac models.