A 400cc ATV is an all terrain vehicle designed for off-road driving. The size of the vehicle is measured by the engine's displacement, which is measured in cubic centimeters, or cc. A 400cc ATV is therefore an ATV that features a 400 cubic centimeter engine. This is considered a mid-size vehicle that is intended for use by adults only because the power output is high enough that a child, or even a smaller adult, may not be able to safely operate the vehicle without losing control. Like other sizes of ATVs, the 400cc vehicle can feature a variety of designs intended for different purposes.
Sport utility ATVs are designed for hauling and towing rather than for speed, so a 400cc ATV in this case will usually feature a wider footprint for stability and accessories geared toward making hauling or towing much easier. Racks can be installed on the body for supporting various items, and a towing system is likely to be included with this style of ATV so a trailer can be attached to the unit. This style will differ from a 400cc ATV designed for racing; such vehicles will feature high ground clearance, long travel suspension for withstanding jumps, and a light frame and body to ensure higher speeds and better maneuverability.
Regardless of the design, the engine size of a 400cc ATV will remain the same. The speeds the ATV can achieve will vary according to the weight of the vehicle as well as the aerodynamics of the body. Heavier ATVs cannot generally achieve the high speeds a racing ATV can, but a racing ATV will not be suitable for hauling, towing, or other heavy-duty applications.
A third type of ATV is sometimes known as a UTV, or utility terrain vehicle. Unlike traditional ATVs, the UTV will feature side by side seating for two riders, or in some cases four seats for four riders. The UTV may also feature a utility bed for hauling materials or storing items, and the UTV may feature a canopy over the drivers and passengers for protection from the elements as well as safety in the event of a rollover. A 400cc ATV in this style is usually meant for utility use, such as groundskeeping, though it can also be used for recreational purposes. Four seat models generally will feature a larger engine to handle the extra weight; an 800cc engine, for example, is quite large and will be able to handle the weight while still achieving reasonably high speeds.