In general, Super Jeep and Super Trucks are modified vehicles expressly intended for off-road adventures. By definition, these vehicles must have tires larger than 38 inches in diameter. Super Jeeps are usually equipped with VHF radios and satellite navigation systems. These terms are not to be confused with 4x4 vehicles or SUVs. Four-wheel drive, or 4x4/4WD, refers to any vehicle with four wheels total, all of which rotate. Certain roads in Iceland, such as F-roads, are only accessible with a 4x4 or higher category of vehicle. An SUV is a sports utility car, meant for spacious interiors and some off-road capabilities. Neither of these vehicles are Super Jeeps, however.