The thirty scrutineers, all volunteers, have been hard at work since the scrutineering session and their task continues once the race is running. They monitor the cars using the telemetry system and collect the data they need to check that everyone is playing by the rules.

Magneti Marelli has set up 29 wi-fi aerials around the circuit, to monitor the position of the cars and operate the marshalling system. Race Control uses the system to inform drivers of slow zones and safety car periods.

Officials know who is at the wheel at all times. Which is more important than it may seem. The rules stipulate a minimum weight for the empty car. But when drivers bring the car onto the ramp, they stay inside, which is why at scrutineering, they are weighed with their helmets.

Also during scrutineering, the pit marshals ensure that the fuel tank complies with rules and that performance cannot been illegally enhanced by additives in the fuel provided by the race organiser. Official supplier Total analyses a sample of fuel in a mobile laboratory.

If the pit marshals have doubts about team proceedings during pit stops, they ask for the scrutineers’ opinion. If necessary, the officials may decide to impose a penalty.

Being a scrutineer at Le Mans is no mean feat. Once the race is over, they still have plenty to do.

On Monday, we’ll take a look at what their post-race job involves.

Photo: LE MANS (SARTHE, FRANCE), 24 HOURS OF LE MANS. Marshalling screen in the cockpit.