Cars with four-wheel drive provide more traction than those with two-wheel drive. Traction is what keeps a car moving forwards. Traction is different to grip, which stops a car sliding or skidding when going around a corner. Cars with four-wheel drive have more traction because less power is being sent to each wheel compared with a two-wheel drive car - the ‘load’ is more spread out. That means the wheels receiving power are less likely to spin on a slippery surface.
Cars with four-wheel drive are very effective on slippery roads, whether caused by rain, mud, ice or snow. Setting off from a standstill in such conditions, a two-wheel drive car is more likely to spin its wheels, which can make it difficult to get going. The increased traction of four-wheel drive can make the difference.
While not infallible, four-wheel-drive cars are generally easier and safer to drive on slippery roads, giving a real feeling of security and reassurance. The extra traction also means cars with four-wheel drive cars are better for towing. And four-wheel drive is pretty much essential for serious off-road driving.