Two-wheel drive (2WD) describes vehicles with a drivetrain that allows two wheels to receive power from the engine simultaneously.
For four-wheeled vehicles (and by extension, vehicles with six, eight, or more wheels) this term is used to describe vehicles that are able to power at most two wheels, referred to as either front or rear-wheel drive. The term 4×2 is also used, to denote four total wheels with two being driven. Most road vehicles use a 2WD layout due to its light weight and simplicity. Traction on the road is usually sufficient that the driving force can be reliably transmitted through only two wheels.
Chevrolet introduced the designs, choices and build-your-own features for the 2015 models on its website in January 2014 with a set price starting at $47,000 (2WD) to $50,000 (4WD) for the LS trim, $52,000 (2WD) to $55,000 (4WD) for the LT trim, and $61,000 (2WD) to $65,000 (4WD) for the LTZ trim. The pricing on GMC's Yukon XL's are set at around $49,000 (2WD) to $52,000 (4WD) for the SLE, $57,000 (2WD) to $60,000 (4WD) for the SLT, and $65,000 (2WD) to $68,000 (4WD) for the Denali trims.
For vehicles that have part-time four-wheel drive, the term refers to the mode when 4WD is deactivated and power is applied to only two wheels.
For two-wheeled vehicles such as motorcycles and bicycles, the term is used to describe vehicles which can power the front as well as the back wheel. The term 2×2 is also used to denote two total wheels with both being driven. 2×2 vehicles are typically either mechanically driven via chain or shaft or are hydraulic driven.
This scheme greatly improves offroad performance, but is quite complicated and requires more power to operate, thus most 2WD machines are either "exotic" bikes for enthusiasts or created with special uses in mind.
Manufacturers who have one in production include Rokon and Christini. Manufacturers who are working or have worked on a prototype include ZID, Suzuki, Yamaha, KTM, and Honda.