Inside their high-tech Formula 1 factories, Mercedes and Williams are in a constant cycle of pushing the boundaries in the car build. And the clock is ticking. With just a few weeks to go until the start of the 2024 season, Williams are working overtime as the final components of the car go into manufacture. Team principal James Vowles says these crucial weeks towards the end of January are the busiest time for the workforce at his Oxfordshire facility, bar none. But what will be the very last piece of the car to be made? Sarah Holt and Holly Samos are going inside the factories to find out. At the Mercedes factory in Brackley, COO Rob Thomas is aware time is now at a premium. The wind tunnel is still hard at work trialling aerodynamic upgrades that hold the promise of more performance on track. They then need to be put into production - but can the factory afford to leave it as late as possible to give the wind tunnel team more time? There are still some important milestones to go in the car build and for Mercedes’ technical director James Allison, that’s a cause for sleepless nights. Both factories are working as one to deliver the 2024 race cars for their star drivers in time to go racing at the opening Bahrain Grand Prix on 2nd March. The race team, who travel to the races around the world, are also honing in on their preparations. For the pit crews at Williams and Mercedes, it’s time to rehearse the quicksilver pit-stops that can make - or break - a race weekend.F1:Back at Base was created and produced by Holly Samos and Sarah Holt and is an IMG Production for the BBC.