how much faster can you go in a 4x4?

peasant

Imagine a snow covered, straight road. Imagine further that you can drive this road in a 2 wheel drive car safely at 50 km/h and at 51 km/h you would loose traction and spin.

So how much faster can you go in a car with four driven wheels?

a) twice as fast
as there are twice as many wheels in contact with the road, you can drive twice as fast before you lose grip

b) 25% faster
as the momentum of the vehicle rises exponentially to the speed, you can only increase the speed by one quarter until you reach the same critical forces on all four tyres that the 2WD has at 50 km/h

c) not one single kilometre per hour faster
because in case you need to brake, 4WD has no advantage over 2WD

unkel

50km/h is plenty fast on a snow covered road, RWD, FWD or 4WD

Kashkai

A typical 4 x 4 is also at least 50% heavier than a normal car and thus it would take longer to stop on a road that is covered in snow/ice/or wet road.

I had a Kia Sportage up to recently and while it was fast, it rolled like a boat in bends. Glad I'm back in a normal hatch that doesn't eat fuel and will corner safely.

peasant

Prosperous Dave wrote:

A typical 4 x 4 is also at least 50% heavier than a normal car and thus it would take longer to stop on a road that is covered in snow/ice/or wet road.

Bingo !

100 points and an inflatable washing machine to our winner !!

You're correct ...you should actually be driving slower than a "normal" car in these conditions.

JohnBoy

peasant wrote:

So how much faster can you go in a car with four driven wheels?

is it an offroader or a subuaru imprezza you're asking about?

peasant

JohnBoy wrote:

is it an offroader or a subuaru imprezza you're asking about?

In the 4WD Subaru Impreza you shouldn't go any faster than in a 2WD Impreza ...in a 3 ton lump of an offraoder should take it that bit more slowly.

Panda Moanium

Bear in mind also that 4WD doesn't give you more grip, just better traction. They are quite different things.

So in other words it will pull you up a slipppery hill better than a 2WD vehicle, but is no help in slowing you for a corner. Indeed 4WD won't help in getting you around a corner either unless you are a highly skilled rally driver that can set the car up to powerslide through....not something that is advisable on public roads....

cancan

Tyres make the biggest difference.

Throw a set of snow tyres on a rental fiesta, and on a snow covered road, it will hand an Impreza STI with summer tyres and active diffs it's ass.

People sometimes think that because they have 4WD, they can drive like nutters when there is snow on the ground.

Foolish thinking.

Braking distances do not change.

4WD only provides an advantage on getting power down, and a marignal difference on turns.

Hence, you are more likley to have an off in a 4WD, as you are likley to have attained a higher top speed, but your ability to slow the car has not changed.

For regular snow driving, snow tyre are a very important purchase, whether on a 4WD car or not.

crosstownk

Panda Moanium wrote:

Bear in mind also that 4WD doesn't give you more grip, just better traction. They are quite different things.

So in other words it will pull you up a slipppery hill better than a 2WD vehicle, but is no help in slowing you for a corner.

Well said.

It's important to remember the term - Four Wheel DRIVE - not Four Wheel Stop. All 2WD cars have brakes on the four wheels.

Do-more

Anyone remember the Top Gear test when they compared the braking distances of a Ford Escort, old Anglia 105E and a Land Rover Discovery? LOL and people think that SUV's are "safe" more like you are twice as likely to be involved in a crash in one!