Car Advice

Volkswagen Amarok’s ‘offroad’ button and how it helps you stop on dirt

19 Jun 2015

Robert Pepper 3

The Volkswagen Amarok has an unusual button. It’s marked “Offroad”, BUT it’s incorrectly named as it should be called “Dirt Roads and Stuff”. 

THE VOLKSWAGEN AMAROK has a button marked “offroad” and this button sets up the Amarok’s electronics for offroad use.  It it enables the “downhill driving assistant” which is better known to everyone else as Hill Descent Control, which is the name Land Rover actually coined for it.  Another function it performs is to recalibrate the ABS system so that it performs better on dirt roads.

ABS is there to prevent wheels locking when you brake.  This is primarily so you can retain steering control when braking hard, as a locked wheel means you’ve lost any hope of steering and therefore quite possibly living.  ABS systems have wheel speed sensors which detect a wheel about to lock and release the brakes fractionally and momentarily – it doesn’t necessarily wait till the wheel has completely locked.

A myth is that ABS stops you quicker.  Well, it’s not a complete myth.  On wet roads ABS works wonders as most drivers could and would lock the brakes, so the tyres’ ability to clear water and grip the road underneath is limited.  That means you’d aquaplane on to disaster.  On dry roads fully locked wheels are quite good at stopping you quickly, but again you’d lose steering control.

A historic problem with ABS on dirt roads was that it didn’t let the wheels lock up enough to properly retard the vehicle.  The looser the surface, the more effective it is to allow the tyres to dig into the ground, biting into the hard grip under the loose top, or to build up a wedge in front of the tyres.  Newer ABS systems are much better, as they are programmed to detect dirt roads and adapt their braking to suit, and indeed Australia is something of a leader in this sort of design.

The Amarok takes things further with its Offroad button, and the difference in stopping power can be felt quite easily.   Without Offroad enabled the ABS, to my feel, is substandard on dirt.  With Offroad enabled it is excellent.  To determine the difference we carried out a little test.

The ‘Rok hit two Maxtrax at the top of a hill by a cone at 100km/h, at which point  the driver, Bearded Stig. slammed the brakes on.  With Offroad disabled the vehicle took 95m to come to a halt.  With Offroad enabled that was cut to 78m, or 20% and 16.5m better.  Those distances are long, but remember there’s a hill involved which was intentional, firstly because it made the photography easier, and secondly because it made the braking more of a test.   Steering control could be retained in both cases, and we did a couple of runs to average the results.

So what’s to conclude?  Firstly, modern ABS can do a great job of dirt-road stopping, as this test shows the difference between a dirt-road and normal calibration.   I also know from previous tests with and without ABS that modern ABS stands up well to a non-ABS stop on dirt roads.  Secondly, always drive your Amarok on dirt roads with the Offroad switch on!

The Amarok also has two other brake technologies, EBD and EBA, as indeed do virtually all cars these days.

EBD is electronic brake distribution – the system increases braking power on given wheels for maximum effect, as distinct from normal ABS which just stops a wheel locking.  In roadcars, the front brakes are set to lock before the rears because that’s safer, so at maximum braking effort there’s still some traction left on the rear wheels.  EBD ensures every wheel is braking to the maximum.

EBA is electronic brake assist, a system that detects if you’re trying to do an emergency stop by working out how quick you came off the throttle and onto the brake.  If it reckons you’re trying to stop very quickly it’ll help apply maximum braking pressure, as most drivers don’t do this as they rarely, if ever, do emergency stops.