F1 Scrutineering Explained: Car Checks and Disqualification

The Belgian Grand Prix of 2024 finished with George Russell crossing the line first in a Mercedes that had made one stop all afternoon. A few hours later he was not the winner. The car, weighed with Russell aboard after the race, was 1.5 kg under the minimum weight. The stewards disqualified him, Lewis Hamilton was promoted to victory, and every driver behind them moved up a place. Nobody alleged cheating. A tyre-saving one-stop race had worn off more rubber and burned off more fluid than the team had planned for, and the scale did not care why.

That is scrutineering. In Formula 1 it is the FIA's process for checking that every car complies with the Technical Regulations, and it runs before, during and after each event. The cars are inspected and measured in an FIA garage near the end of the pit lane, weighed on its weighbridge during practice, qualifying and after the race, and sampled for fuel. A car found outside the rules is reported by the FIA technical delegate to the stewards, and the stewards almost always disqualify it. There is no margin for a breach "too small to matter", and no defence that the breach gave no advantage. The rest of this guide explains the checks in the order they happen, then the cases that made the rules what they are.

Scrutineering explained: the FIA's check on every F1 car

Scrutineering exists because the Technical Regulations are long, precise and full of numbers, and a rule that is not checked is a rule that will be bent. The checks are carried out on behalf of the FIA by its technical department, led at each event by the technical delegate. Every car is subject to inspection at any point during a Grand Prix weekend.

There are three stages. Before the event, teams submit paperwork and the cars go through initial checks. During practice and qualifying, cars are called to the weighbridge at random and may be inspected. After the race, the finishers are weighed, fuel samples are taken, and some cars are selected for detailed inspection.

The FIA does not need to prove intent. A car is either inside the regulations or not. That principle sits at the heart of every disqualification covered in this guide, and it is the principle fans find hardest to accept when a driver loses a result for a reason invisible to the naked eye.

Check	When	What is measured
Declaration of conformity	Before the event	Team confirms the car complies with the regulations
Random weighing	Practice and qualifying	Car weight, with the driver weighed separately
Post-race weighing	After the race	Car and driver weight against the minimum
Fuel sample	After the race	At least one litre drawn and analysed
Plank and floor	Selected cars after the race	Plank thickness and floor dimensions
Bodywork and wings	Throughout the weekend	Dimensions and deflection under load

The output of the process is the technical delegate's report. If a car is found to be in breach, the report goes to the stewards, who hear the team and decide. Our guide to the stewards and the race director explains how the stewards are appointed and how they reach their decisions.

Who does the checking: the technical delegate and the FIA garage

The technical delegate is the FIA official responsible for checking that the cars comply with the regulations at each event. He heads a team of scrutineers, engineers and technicians who travel to every Grand Prix. The team is small by comparison with the people employed by any single Formula 1 team, so the checks have to be targeted.

The FIA garage is near the end of the pit lane. It is a working inspection bay with a weighbridge, a reference plate and the equipment needed to measure the cars.

The weighbridge

The weighbridge is a set of scales, built into the floor of the FIA garage, on which a car can be pushed and weighed. Weighing a car takes seconds, which is why random weighing during practice and qualifying is possible without holding up the session.

The reference plate

The reference plate is a flat, level surface on which the car can be placed so that its dimensions can be measured accurately. Formula 1's regulations define many dimensions relative to a reference plane, and the plate allows the scrutineers to check them. The heights of the wings, the shape of the floor and the dimensions of the bodywork can all be checked against templates and gauges with the car on the plate.

Tools of the trade

Scrutineers carry an array of measuring tools, from the gauges used to check the plank to rigs that apply loads to wings and floors. They also use the data the cars generate. Every car runs an FIA-specified data logger and sensors, and the technical department has access to the data, including fuel flow and power unit parameters. Some checks are carried out remotely by analysing data rather than by putting a gauge on a part.

The size of a team's own engineering department dwarfs the FIA's, which is one reason the process has shifted towards audits and data, as the next section explains. The difference between the people who build the cars and the people who check them is covered in our guide to F1 team structure and roles.

Self-scrutineering and the declaration of conformity

Formula 1 cars are too complex for the FIA to inspect every part at every event. Instead, the burden is placed on the teams. Before each event, each team must declare that its cars comply with the regulations. This is sometimes called self-scrutineering.

The declaration is not a formality. It is a statement on which the team can be held to account. If a car is later found not to comply, the declaration becomes part of the case: the team has certified something that was not true.

From inspecting everything to auditing

In earlier decades, initial scrutineering involved the FIA examining each car on a set day before the event. The process shifted as the cars became more complex. Teams submit detailed information to the FIA about their designs, and the FIA reviews the designs rather than relying solely on physical inspection at the track. Physical checks at the event are then targeted, using random selection and the FIA's own judgement of where the risk lies.

This approach mirrors the way financial auditors work. The aim is not to inspect everything, but to make the probability of being caught high enough that no team will take the risk. A team that knows any car can be selected at random, any part can be measured and any data can be examined has a strong incentive to stay inside the rules.

Checks before a car turns a wheel

Some of the most important checks happen months before the first race. Every chassis design must pass a series of FIA crash and load tests before it can race: impacts on the front, side and rear structures, squeeze tests on the survival cell and loads on the roll structures and the halo. The tests are witnessed by the FIA and carried out at approved facilities, Cranfield in Bedfordshire among them, close to the English bases of most of the teams. A chassis that has not passed them cannot be entered, however fast it might be. These are the checks fans never see, and they matter more to a driver's safety than anything measured in the garage on a Sunday evening.

What the teams must provide

The teams must also allow the FIA access to their designs, their data and, under the cost cap and other regulations, their factories. The FIA can ask for drawings, CAD models and information about specific components. If the FIA suspects that a design does not comply, it can ask the team to demonstrate that it does.

The system relies on trust, backed by sanctions severe enough to make the trust rational. When it fails, the penalties are heavy. The final section of this guide covers two cases in which teams were found to have broken that trust.

Checks during practice and qualifying

During practice and qualifying, the FIA can call any car to the weighbridge at random. When a car is selected, the driver is shown a signal as he enters the pit lane, telling him to go to the FIA garage instead of the team's own garage. The car is weighed, and the driver is weighed separately if required, before the team can take it back.

The driver must not miss the signal. If a car selected for weighing fails to stop at the FIA garage, the driver may be required to start the race from the pit lane. The sanction is severe because missing the weighbridge could allow a team to make an illegal car legal before the weighing. Teams brief their drivers carefully, and engineers remind them by radio when a weighbridge call is likely.

Fuel flow and the data

Some checks are made through data, not in the garage. Under the turbo-hybrid rules from 2014, the FIA fitted a fuel flow meter to every car and set a maximum flow rate. At the 2014 Australian Grand Prix Daniel Ricciardo finished second for Red Bull in his first race for the team and was disqualified because the car's fuel flow had exceeded the limit. Red Bull argued that the FIA's sensor was unreliable and that it had used its own calculation instead. The Court of Appeal upheld the disqualification. The case set the rule that a team must follow the FIA's measurements and instructions, even if it believes them to be wrong, and raise its concerns through the proper channels.

Qualifying fuel

The fuel rules apply in qualifying too. A car must be able to return to the pit lane under its own power and provide a fuel sample after qualifying. Lewis Hamilton lost pole position at the 2012 Spanish Grand Prix when McLaren told him to stop on track after qualifying because the car did not have enough fuel left to return and provide a sample. He was sent to the back of the grid. Sebastian Vettel was excluded from qualifying at the 2012 Abu Dhabi Grand Prix after his Red Bull could not provide the required fuel sample, and he started from the pit lane.

Parc fermé

Once qualifying begins, parc fermé conditions apply. The teams can only do limited work on the cars between qualifying and the race, under the supervision of FIA scrutineers. Any work outside those limits requires the car to start from the pit lane. The rules about what can be changed, and the exception for wet weather, are covered in our guide to F1 wet weather rules.

After the flag: weighing, the fuel sample and the deeper inspection

The race ends and the cars go to parc fermé. From there, the post-race checks begin.

Every classified car is weighed, with the driver. The driver is weighed separately, in race kit, and the car's weight is added to give the total checked against the minimum. Fluids and fuel cannot be added before the weighing.

The FIA then takes a fuel sample of at least one litre. The sample is analysed to check that the fuel matches the specification that the team's supplier declared to the FIA before the event. A car that cannot provide the sample is in breach.

Sebastian Vettel lost second place at the 2021 Hungarian Grand Prix in exactly this way. His Aston Martin could not provide the full one-litre sample after the race. The team argued that there was enough fuel in the car but that a fault in the fuel system prevented it being drawn. The stewards disqualified him.

The deeper inspection

Beyond the weighing and the fuel sample, the technical delegate selects a smaller number of cars for detailed inspection. The selection can be random or targeted. Items checked can include the plank, the floor, the bodywork, the power unit and the gearbox. Some checks take hours, which is why disqualifications are often announced long after the podium ceremony.

1. 1Parc ferméCars are taken to parc fermé, where no work may be done without FIA supervision.
2. 2WeighingEvery classified car is weighed, with the driver weighed separately in race kit.
3. 3Fuel sampleAt least one litre of fuel is drawn and checked against the declared specification.
4. 4SelectionThe technical delegate selects cars for detailed inspection of the plank, floor and other parts.
5. 5ReportAny breach is reported to the stewards in the technical delegate's report.
6. 6DecisionThe stewards hear the team and decide, usually disqualifying a car found outside the rules.

The general sequence of post-race checks; the technical delegate decides which cars receive detailed inspection and in what order.

The plank: ten millimetres and one millimetre of wear

Under every Formula 1 car is a plank. It runs along the centre of the floor, and it is ten millimetres thick when new. After the race, it must measure at least nine millimetres at the designated measuring points. A plank worn below that limit is a breach of the Technical Regulations.

The plank was introduced in 1994. It was a response to the cars of the time running as low as possible to maximise downforce. The plank, originally made of a wood-based composite, is a physical limit on how low a car can run. If the car runs too low, the plank wears away on the track surface.

Where it is measured

The plank is measured at specific points, around holes drilled through it. Titanium skid blocks are fitted at some of these points to protect the plank from wear, and their own wear is also limited. The thickness is checked with gauges at those holes, so wear between the measuring points is not what decides the case.

The cases

The first high-profile plank disqualification came at the 1994 Belgian Grand Prix, the year the plank was introduced. Michael Schumacher won the race for Benetton but was disqualified when his plank was found to be worn below the limit. Benetton argued the wear was caused by a spin over a kerb, but the stewards rejected the explanation.

The issue returned with the ground-effect cars introduced in 2022. These cars run very low to the ground to make the floor work, and teams are tempted to run them as low as possible. At the 2023 United States Grand Prix, Lewis Hamilton and Charles Leclerc were both disqualified for plank wear. At the 2025 Chinese Grand Prix Hamilton, by then driving for Ferrari, was disqualified for plank wear, while his team-mate Leclerc and Alpine's Pierre Gasly were excluded for underweight cars. At the 2025 Las Vegas Grand Prix both McLarens, driven by Lando Norris and Oscar Piastri, were disqualified for excessive plank wear. The McLaren case drew particular attention because it came during the championship run-in; the McLaren history page covers the team's longer record.

• 10Plank thickness when new (mm)
• 1Plank wear allowed (mm)
• 1Fuel sample required after the race (litres)
• 85Maximum DRS slot gap at the 2021 São Paulo GP (mm)

The plank and fuel figures have stood in the regulations for many seasons and are restated in each edition; the DRS slot limit applied until DRS was removed for 2026.

Minimum weight: why a car can finish under it

The Technical Regulations set a minimum weight for the car, and it applies at all times. The figure has changed many times: it rose through the turbo-hybrid era as power units, safety structures and larger wheels added mass, and it was reduced for the 2026 cars. The principle has not changed: a car may not be lighter than the minimum at any time during the event.

The driver is part of the calculation, and the rules treat that carefully. Since 2019 the driver and seat together have been required to reach a minimum figure, with ballast placed around the seat to make up any shortfall for a lighter driver. Before that change, a taller, heavier driver carried a penalty in lap time that his team could do nothing about, and some drivers dieted hard to compensate. The allowance put an end to that, and it means the scales after a race are not measuring who ate breakfast.

Teams aim to build cars as close to the minimum as possible, because extra weight costs lap time. They then use ballast to bring the car up to the minimum and position the ballast to improve the car's balance. The margin is small, and a car can finish below the minimum through tyre wear, fuel consumption and fluid loss.

George Russell at Spa in 2024

George Russell's Mercedes at the 2024 Belgian Grand Prix is the clearest example. Russell made one pit stop where most of the field made two. His tyres wore more than usual, and the car finished below the minimum weight. The minimum at the time was 798 kg; Russell's car was measured at 796.5 kg. The stewards disqualified him.

Minimum weight in 2024798kg

Russell's car after the race796.5kg

Minimum weight under the 2024 Technical Regulations against the weight recorded for Russell's car after the race; the shortfall was 1.5 kg.

Show the numbers

The 2024 Belgian Grand Prix weight check

Item	Value
Minimum weight in 2024	798kg
Russell's car after the race	796.5kg

Mercedes did not dispute the measurement, accepted that it had got its calculation wrong, and did not appeal. Hamilton, who had finished second, was promoted to victory.

That is also why drivers weave across the track on the slowing-down lap after the flag. Running through the marbles, the balls of discarded rubber that collect off the racing line, sticks some of them to the tyres and adds a little weight back. It is legal, it is routine, and it is a last line of defence rather than a plan. On a day when a team's calculations are out by more than a few hundred grams, nothing collected on the cool-down lap will close the gap.

Flexible bodywork: load tests and technical directives

The Technical Regulations say that bodywork must be rigidly secured and immobile. In reality all bodywork flexes, so the regulations define tests that set limits on how much it can flex. A load is applied to the wing or floor, and the deflection is measured. If the deflection is within the limit, the part passes.

The tests are a compromise. They cannot replicate the full range of loads that a car experiences on track. A team can design a wing that passes the test but flexes more at high speed, reducing drag on the straights while generating downforce in the corners. Passing the test is necessary but not sufficient: the regulations still require the bodywork to be rigid, and a part that flexes too much on track can be ruled illegal even if it passed the static test.

Technical directives

When the FIA believes a team is exploiting the gap between the test and the rule, it can issue a technical directive. A technical directive clarifies how the FIA will interpret and enforce the regulations, and it can tighten the tests in mid-season. A technical directive in 2022 aimed at the porpoising of the new ground-effect cars added checks on floor flexibility and plank wear. In 2025 the FIA tightened the front-wing deflection tests from the Spanish Grand Prix onwards, after concerns about wings that flexed at speed.

A well-known example came in 2021. Rivals complained that Red Bull's rear wing was flexing backwards at speed to shed drag, and the FIA introduced stricter load tests on rear wings from the French Grand Prix that June, giving teams a short period to adapt. No car was disqualified. The rules had been rewritten around the gap instead, which is how most flexi-wing arguments end.

The cat-and-mouse

Technical directives are contentious. A team whose design is ruled out in mid-season may lose the investment it made in that design. A team that complained about a rival's design may gain an advantage. The FIA tries to issue directives early enough to give teams time to adapt. The process is political, and teams lobby hard on both sides of each directive.

Measurements in fractions of a millimetre

The 2021 São Paulo Grand Prix showed how precise the checks can be. After Friday qualifying, which set the grid for the sprint, Lewis Hamilton's Mercedes was found to have a rear wing that breached the regulations. With the DRS open, the gap between the main plane and the flap was not allowed to exceed 85 mm, a limit that lapsed when DRS was dropped from the 2026 cars. On Hamilton's car, the gap exceeded the limit in one place by a fraction of a millimetre.

The stewards disqualified Hamilton from qualifying. He started the sprint from the back of the grid. He then took a five-place grid penalty for a new power unit element, but drove through the field and won the race on Sunday.

Why the size of the breach makes no difference

Mercedes argued that the breach was tiny and the result of damage rather than design. The stewards accepted that there was no intent but found that the car was in breach, and the regulations do not allow a tolerance for breaches. A car is either legal or not. A rule that allowed small breaches would create an argument about how small is small enough, and teams would design cars to exploit that margin.

Teams know this and design with it in mind. A designer working to an 85 mm limit does not aim for 85 mm. He aims for a figure safely inside it, allowing for manufacturing tolerances, the flex of carbon under load and the damage a part may pick up in a race. The art is to give up as little as possible to that margin. Hamilton's case suggested how small the margin can become: a wing built to the limit, slightly distorted, and a breach measured in fractions of a millimetre.

The principle applies to every measurement. A plank worn by 0.1 mm too much is a breach, just as one worn by 1 mm too much is. The scrutineers do not weigh the size of the breach, and the stewards follow the same approach. More of Hamilton's record is on our Lewis Hamilton records page.

Why "no advantage gained" is not a defence

Teams caught with an illegal car often argue that the breach gave no performance advantage. The stewards have consistently rejected that argument.

The International Sporting Code says that a car that does not comply with the regulations in every respect is not eligible. Whether a breach gave an advantage is irrelevant. The rule is strict because the alternative would be impossible to apply. The stewards would have to assess the performance effect of every breach, and teams would argue that every breach gave no advantage.

Rival teams can also start the process. A protest by one team against another's car obliges the stewards to investigate. At the 2018 Italian Grand Prix Renault protested the floor of Romain Grosjean's Haas after he had finished sixth. The stewards found the floor did not comply with the regulations as the FIA had clarified them, and Grosjean was disqualified. Protests are not common, because they cost money, create enemies and can be turned around: a team that protests one design invites scrutiny of its own.

What can be appealed

A team that disagrees with a stewards' decision can appeal to the FIA International Court of Appeal. The team must give notice of its intention to appeal shortly after the decision and then lodge the appeal. Teams can also request a review of a decision if they find new evidence within a limited period.

Appeals over technical breaches are rarely successful. The measurement is a matter of fact, and the court generally accepts the FIA's measurements. Teams can argue that the measurement was wrong or that the regulation was interpreted incorrectly, but they cannot argue that a breach should be overlooked because it gave no advantage.

The cost of appealing

The appeal process can also produce worse outcomes. In 2005, as the final section explains, BAR appealed against a decision and the Court of Appeal increased the penalty. Teams weigh that risk when they decide whether to appeal.

How a disqualification changes the result

The results published immediately after the race are provisional. They become final only after the post-race checks are complete and any protests have been resolved. That can take several hours.

When a car is disqualified, the driver is removed from the classification. Every driver who finished behind moves up a place, and the points are redistributed according to the new order. The disqualified driver scores no points for that race, and the team loses the constructors' points too. The effect on the constructors' table is explained in our guide to the constructors' championship.

Race	Car	Breach	Result
1994 Belgian GP	Benetton, Michael Schumacher	Plank wear	Disqualified from the win
2005 San Marino GP	BAR, Jenson Button and Takuma Sato	Car underweight without fuel	Disqualified and two-race ban
2021 Hungarian GP	Aston Martin, Sebastian Vettel	Fuel sample not provided	Disqualified from second
2023 United States GP	Mercedes and Ferrari, Hamilton and Leclerc	Plank wear	Both disqualified
2024 Belgian GP	Mercedes, George Russell	Underweight	Disqualified from the win
2025 Las Vegas GP	McLaren, Norris and Piastri	Plank wear	Both disqualified

The podium that has already happened

The podium ceremony takes place before the checks are finished, so a driver can lift a trophy and spray the champagne for a result that no longer exists by the evening. The official classification is what counts. Russell's name went into the record books as a disqualification at Spa in 2024, whatever was photographed on the podium, and Hamilton is listed as the winner. The order of events is unlikely to change, because the alternative is to hold every crowd and broadcaster for hours while the scrutineers work through the cars.

The heaviest sanctions on record: BAR in 2005 and Tyrrell in 1984

Disqualification from a race is the usual sanction. Two cases went further.

BAR in 2005

At the 2005 San Marino Grand Prix, Jenson Button finished third and Takuma Sato fifth for BAR. The FIA found that the cars could run below the minimum weight once their fuel was drained, because a separate compartment in the fuel system held fuel that was not drained when the car was emptied. The stewards initially cleared the team, but the FIA appealed.

The Court of Appeal found against BAR. It disqualified both cars from the race and banned the team from the next two Grands Prix, in Spain and Monaco. BAR denied any intention to cheat, but the court found that the design was outside the rules. The Jenson Button career page covers the season in which the ban fell.

Tyrrell in 1984

The Tyrrell team was excluded from the entire 1984 world championship. The case centred on the team's practice of adding water and lead shot to the car during late-race stops, which brought the car up to the minimum weight at the end of the race after running underweight earlier. The FIA found the team in breach and removed all of its results for the season, including Martin Brundle's second place in Detroit.

The case was also political. Tyrrell was the leading holdout against turbocharged engines and was opposing changes to the fuel rules that the turbo teams wanted, and its exclusion took its voice out of that argument. Whether that motive played any part has been argued ever since, and the evidence is circumstantial. The Tyrrell F1 history page covers the case in full. Both sanctions remain unusual. They show that scrutineering is not only about the measurements on a single day but about the team's honesty with the FIA over a season. The motorsport hub has the rest of our Formula 1 explainers.