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The ins and outs - and back in, and out again, and back in again - of testing. Over the next three days, you’ll see the cars drive in and out of the garage plenty of times, but before that hotly anticipated first time, we’ve compiled an easy-to-understand guide to cover the basics of pre-season testing.

We’ve done our fair share of Formula 1 tests, but if this is your first, then you’ve come to the right place. From where and when, to why, and what that metal fencing is hanging off the car, this is your beginner's guide to Formula 1 testing.

What is pre-season testing?

If you’re a fan of football, the NFL, Rugby or the NBA, then testing is our equivalent of a pre-season-friendly schedule. 

So, like how Liverpool played Sevilla last August, or the Kansas City Chiefs played the Detroit Lions that same month, we’ll head off for some warm weather testing in Bahrain. The aims are also pretty similar. It’s a good chance to get the whole team up to speed and it’s also great for supporters who have been starved of racing action since the end of the season. 

For those not interested in other sports, think of it a little like cooking. If you’re hosting a dinner party, you might try making the main dish a few days beforehand to perfect the recipe, trial different ingredients and quantities, and maybe find a wine pairing. 

Got it – so what are you cooking up?

The MCL39, our freshly built 2025 Formula 1 challenger. We’ve got our fresh ingredients ready, we now need to try them out. 

What do you test?

For starters (pun not intended), they need to check that everything works and is in order… So, you know those checks that you should always do on your car every week, that you actually only do every couple of months? The windscreen wiper fluids, oil levels, tyres, etc.? Well, F1 has their own versions, and our team does them religiously. All pretty basic checks, but vital ones, nonetheless.

However, the main aims are to find performance and expose issues, improving reliability. There are all sorts of ways to do this, but a big part of testing is data gathering, which can help the team to work out how the actual on-track data correlates with the data they’ve gathered from the simulator. The closer the match, the closer we are to extracting our car’s full potential.

The team will try a multitude of different setups to work out what works best on the MCL39 across different fuel levels and tyre compounds and to find out how far we can push it in different scenarios.

How much time do you have to test?

Every team gets the same amount of official pre-season testing time. This year, we’ll all get three days at the Bahrain International Circuit, from 26 - 28 February, just over a week before the season’s first race in Australia. Running will take place between 07:00 and 16:00 (GMT), with an hour’s break for lunch halfway through each session. 

The three days are split evenly between drivers, with Lando and Oscar both getting a maximum of one and a half days each in the car. Lando will drive the MCL39 in the PM on Wednesday and Thursday and the AM on Friday, while Oscar will get behind the wheel in the AM on Wednesday and Thursday and the PM on Friday. 

How do you gather data?

In all sorts of ways. Performance data can be collected from various sensors on the car, which measure everything from speed and aerodynamics to the G-forces created during cornering and braking and the car’s distance from the ground. In a race, cars feature around 300 sensors, but in testing, this number is much, much higher. There are different types of sensors for different jobs, but that’s an article for another day.

Do the cars go all out?

At some point across the three days, it’s likely that most teams will aim to set a qualifying-style run to assess their maximum performance and test out reliability, but this doesn’t necessarily mean we’ll get a true picture of who is good and who isn’t, because these runs could come at different times of day on different track conditions.

Are there any benefits for the driver?

Absolutely! Although Lando and Oscar have kept busy over the past few months in the gym, on the simulator and even out on track in the old-spec MCL60 from 2023, nothing compares to driving the real thing.

The MCL60 is also very different from our 2025 challenger, so, the chance to get out and drive the cars before the start of the season is massively important.

Not only will it allow the drivers to adjust to the new car and get used to driving it, they will also be able to feedback on their comfort levels, provide their thoughts on the setup and request any changes they require.

Do you look at other teams?

Our full focus is on ourselves and ensuring we’re ready for Round 1, but we’re just as nosey as the rest of you and will glance a sideways eye at our competitors to get an idea of what they’re doing.

Why is the car covered in scaffolding and paint?

Scaffolding, metal fencing, braces, grills - aero rakes have been called many names in the past, but they do play a key role. You might see teams use several different aero rakes throughout testing, some very easy to spot, and some very difficult to see. But (apart from obstructing our view of the cars) what do they do?

You’ll most likely see them installed directly behind the front tyres or on the rear of a car. They feature a series of sensors and are used to measure the air pressure over the car.

For similar reasons, you’ll also see the cars covered in flow-vis paint. Created from a mixture of fluorescent paint powder and paraffin oil, the mixture dries as the car picks up speed and air flows through the bodywork, leaving fine, detailed patterns for the team to assess.

Both techniques are done as part of data gathering to see whether the airflow matches what we saw in our simulations and confirm it is working correctly.

Why does everyone keep asking if teams are “sandbagging”?

We could do an entire article on strange-sounding F1 terminology, but sandbagging is amongst the most common you’ll hear in testing. In short, this is when teams deliberately don’t show their true lap time potential. They could do this for several reasons, but most often, it’s to hide how good their car truly is from other teams.

On the other end of the spectrum, teams could perform what is referred to as a “glory run,” which is when they make the car as light and as fast as possible to set a lap time that is faster than could realistically be achieved. It’s rarely seen these days, but could be done by teams to impress potential partners, or purely to boost morale in the garage.

Cool! Can I watch?

You can! Testing doesn’t tend to make for the greatest racing spectacle on the planet, but with a brand-new season on the horizon and a lack of (on track) F1 action over the past two months, it always draws plenty of attention. It does depend on where you live, but the test will be shown by major broadcasters in all of the key markets. 

More importantly, don't forget to visit the McLaren App to follow Lando and Oscar's progress, as well as our website for daily team test reports.