A sport utility vehicle (SUV) is a car classification that combines elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. There is no commonly agreed-upon definition of an SUV and usage of the term varies between countries. Thus, it is "a loose term that traditionally covers a broad range of vehicles with four-wheel drive." Some definitions claim that an SUV must be built on a light truck chassis; however, broader definitions consider any vehicle with off-road design features to be an SUV. A crossover SUV is often defined as an SUV built with a unibody construction (as with passenger cars), however, the designations are increasingly blurred because of the capabilities of the vehicles, the labelling by marketers, and electrification of new models. The predecessors to SUVs date back to military and low-volume models from the late 1930s, and the four-wheel drive station wagons and carryalls that began to be introduced in 1949. The 1984 Jeep Cherokee (XJ) is considered to be the first SUV in the modern style. Some SUVs produced today use unibody construction; however, in the past, more SUVs used body-on-frame construction. During the late 1990s and early 2000s, the popularity of SUVs greatly increased, often at the expense of the popularity of large sedans and station wagons. More recently, smaller SUVs, mid-size, and crossovers have become increasingly popular. SUVs are currently the world's largest automotive segment and accounted for 45.9% of the world's passenger car market in 2021. SUVs have been criticized for a variety of environmental and safety-related reasons. They generally have poorer fuel efficiency and require more resources to manufacture than smaller vehicles, contributing more to climate change and environmental degradation. Between 2010 and 2018 SUVs were the second largest contributor to the global increase in carbon emissions worldwide. Their higher center of gravity increases their risk of rollovers. Their larger mass increases their stopping distance, reduces visibility, and increases damage to other road users in collisions. Their higher front-end profile makes them at least twice as likely to kill pedestrians they hit. Additionally, the psychological sense of security they provide influences drivers to drive less cautiously. Definitions There is no universally accepted definition of the sport utility vehicle. Dictionaries, automotive experts, and journalists use varying wordings and defining characteristics, in addition to regional variations of usage by both the media and the general public. The