What does 4WD mean when it appears on the car?

[LondynRose]

4WD stands for four-wheel drive, which is the abbreviation of the English term 4-wheel-drive. Four-wheel drive systems include full-time 4WD, part-time 4WD, and on-demand 4WD. The specific introductions are as follows: 1. Full-time 4WD: Vehicles equipped with a full-time 4WD system are always in four-wheel drive. This system is commonly found in some luxury SUV models, such as the BMW X5 and Audi Q7. 2. Part-time 4WD: This system allows drivers to switch between 4WD and 2WD via a switch inside the vehicle. Most off-road vehicles with part-time 4WD also feature a low-range 4WD function. When switched to low-range 4WD, the wheel torque is further amplified, helping the vehicle escape difficult terrain. Vehicles with part-time 4WD include the Toyota Land Cruiser Prado and Jeep Wrangler. 3. On-demand 4WD: This system is typically used in some urban SUVs or front-wheel-drive vehicles with transverse-mounted engines. Vehicles with on-demand 4WD usually operate in front-wheel drive mode, and power is distributed to the rear wheels only when the front wheels slip or during full-throttle acceleration. On-demand 4WD has lower costs and fuel consumption, making it suitable for urban SUVs and sedans.