Competitors in the World Rally Championship (WRC) are among the best drivers in the world. In fact, many motorsport aficionados would argue that they are absolutely, definitely, the world's best.

After all, which other form of motorsport asks drivers to compete on roads covered in snow, ice, gravel, asphalt, mud or rocks - and in all weather conditions? Then there's the endurance element. Three long days of competition mean thousands of kilometres at the wheel and an awful lot of time spent tightly strapped into the car. But relax for a second and they could be in trouble. The WRC pushes mental concentration and physical fitness to the limit.

There's also the skill and nerve required to drive flat-out on some of the most unforgiving roads in the world. Whether speeding through forests, along cliff edges, or dodging snow banks, ditches or rocks the size of wardrobes, there is never much room for error. There are no gravel traps in the WRC, and no pit-crews nearby to patch things up either. If a car is damaged, the chances are the driver and co-driver will be the ones who have to try and fix it. So they need to be pretty good at do-it-yourself too.

Unlike most other forms of motorsport, rally cars carry two people - a driver and a co-driver. The co-driver, who sits in the front passenger seat, provides the driver with a running commentary on what's coming up on the road ahead.

At every rally, drivers and co-drivers spend two days reconnoitring the route in 'recce' cars. The organisers stipulate a maximum speed of 50-70 kph for the recce and the crew are allowed two runs through each stage. On the first run the driver calls out what he sees on the road - the severity of each corner, and the position of every crest, bump and change of road surface, while the co-driver makes pace notes of the comments. On the second run the co-driver reads the pace notes back to the driver. Any misunderstandings are sorted out there and then until the meaning is crystal clear.

Rallies will sometimes re-use a stage from the previous year, but drivers and co-drivers still recce them, because over 12 months, re-routing and re-grading can completely change the character of a special stage.

On the day before the rally, the crew get the opportunity to check their WRC car during 'shakedown.' To prevent any driver gaining an unfair advantage, the stretches of road used for this do not form part of the rally route, but have similar characteristics to the roads on the special stages.

As well as advising the driver when he can - or can't - safely take a blind hump at full throttle, the co-driver is also the car's administrator. Organisers issue each crew with a time card which lists the times they must be at each time control and it is the co-driver's job to make sure the car is in the right place at the right time. There are penalties for being early as well as late!

Once in a stage the co-driver relays the pace notes to the driver through an intercom system in their crash helmets. The secret here is timing. The information must be delivered at exactly the right moment - not too early and not too late. An added complication is that the co-driver can't see the road too well, because in the interests of a low centre of gravity, his seat is mounted as low a possible. With a typical view of the underside of the dashboard, co-drivers are adept at feeling the direction of the car through the seat of their pants.