It's one of the determining aspects of a Formula One season...
- What are the main areas of the car a team develops during the season?
"Mercedes will focus mainly on three areas: aerodynamics, the Power Unit and the tyres. The aim of aerodynamic development is to find new and better bodywork packages. For the Power Unit, the team will usually pursue two goals. The first is to bring new component designs to the PU; the second is to learn how hard we can actually push the PU.
"At the beginning of the season, the team wants to make sure that the Power Unit runs reliably. As the reliability has to be proved on the dyno, we will usually start a little more conservative to have a product that can run the required mileage.
"Once a reliable base has been established, all subsequent long runs of the engine will focus on trying to extract more power. In those runs, the team will be more willing to push the PU a bit harder on the dyno.
"This is a well-calibrated process as we aim to find the exact limits of the PU without overstepping them - but knowing that if we overstep the mark, there is still a proven configuration on the track. The third focus area for in-season testing is the tyres, because the teams only get to see them for the first time properly in winter testing.
"The tyres are a major performance factor and it takes a while to fully understand them and be able to exploit them to the maximum. This might not necessarily have an impact on the subsequent development and design of the car; it will, however, very likely change the way the team uses the car in order to get the most from the tyres."
- How much time can a team find through in-season development?
"The exact amount of time a team can find over the course of the season is one of the better-kept secrets of this sport - and we aim to keep it that way.
"However, it is sufficient to say that in-season development has considerable impact on the season's result.
"If a team were to stop development of their car after the first race, while all the others brought developments for the rest of the season, that team would drop several positions in the Constructors' standings - simply by not bringing improvements to the car.
"In Formula One, if you don't go forwards, you go backwards."
- How is the development schedule for in-season upgrades determined?
"That depends on the components. For the Power Unit, the development course is mostly dictated by the regulations. With only three PUs for the entire season, the team wants to make sure that the mileage is split relatively evenly between those three.
"Other components are driven by the specifics of the circuit. Monza, for example, typically needs a lower rear wing level than most of the other tracks. So, the team will develop the rear-wing and low-downforce package sufficiently in advance of Monza to be able to construct those pieces for the race weekend.
"For the aero programme, an outline plane will be established that says roughly when you will want to introduce new packages. It's usually spaced to a sufficient degree such that the team is confident that it will have found a decent number of gains which are then brought to the track as a package.
"However, those schedules are very fluid - mostly, because the team can never be sure precisely where the gains are going to come, how big they will be and how easy they will be to implement. Last but not least, there is also the opportunistic kind of development - where someone just has a good idea and the team decides to make it.
"So, while some update packages might have been planned for months, others updates might be brought to the car as soon as the team finds them."
- How important is driver feedback for in-season development?
"Driver feedback plays an important role. While it will rarely change the fundamental performance direction of the car, driver feedback allows the team to modify its approach and make sure the car really suits the driver.
"This is especially true for all aspects of driver comfort, for example seat position, mirrors, steering wheel angle or pedal spacing.
"While those might seem like minor details, they are important to get right as a driver who is uncomfortable won't be able to get the best out of the car.
"While the key ingredients of a fast car are usually universal for all drivers, driver feedback still impacts the performance development of the car, as it helps the team to identify the areas of the car they should focus on in the ongoing development process."
- A tough in-season fight also means that teams will put a lot of effort into the in-season development of the car. How do teams find the right balance of in-season development and working on next year's car?
"A team wants to make sure that it doesn't sacrifice next year's performance for this year's points. However, the decision on when to shift more and more people from this year's development to next year's is not an easy one - especially in a hard-fought fight.
"If a team is miles ahead in the Championship, it's a relatively easy decision because the team can back off early, knowing that the others won't be able to catch up.
"The same is also true for a team that is miles behind, because no matter how hard they try, they won't be able to catch the other team. It gets more difficult when the Championship fight is really close.
"If it is close, a team will tend to give a bit more to the current championship than it might be otherwise comfortable with. The upcoming regulations are also a factor in this equation. They remained fairly stable for the current season, meaning that teams could change over quite late, knowing that it wasn't going to hurt anything in particular.
"For next year, however, the aerodynamic changes in the regulations are quite big, so it would be risky to ignore them."
- How much inspiration do teams draw from the development of other teams and cars?
"When teams see something good that they have not tried before and that looks implementable on their respective cars, they will look at it in simulation or the wind tunnel and, if it is good, they will introduce it on their car as well.
"However, because the concepts of the cars are very different, those inspirations tend to only affect small things in a small way - and they're not easy to implement either."