Preparing a car for this would be incredible. I guess unless you have been involved with race prepping a car for a rally, it is difficult to comprehend. When we were doing selected rounds of the ARC and APRC, we were only doing 2 day events. And tough as these stages are on a car, rally raids like Dakar are something else again, and they go for 2 weeks.
When I say you leave nothing to chance, it does not not convey the level of preparation that is needed. The logisitics alone are a big enough challenge- what with food accommodation, transport, and so on. Training your crew is another aspect that takes time because your budget is low and expenses very high.
Then you look at all the spares you will need. I don't know Dakar rules but we had spare driveshafts, lights, and so on. Think of hubs, strut tops, panels, glass, gearbox, clutch, starter, battery, hoses, tyres, rims, discs, pads- where do you stop? I had a huge box of spare nuts and bolts for the whole car
Then you have to meticulously engineer the car, trying to look out for weak links and make them stronger. I've seen people race prepare a car, only to have brake failure because they did not engineer the attachments of the brake hose and they rubbed against a tyre until it wore through. No brakes. You will need to re-enforce the strut towers, stitch weld the whole front end and much of the rear end around the towers
Then you have the final build, being careful to leave nothing out. You then go over it again, before a thorough bumper to bumper spanner check.
You then have to organise your crew as to who does what, making sure obvious things like re-fuelling are not forgotten. There are a million other things that need doing, and we have not touched sponsorship and keeping the sponsors happy. It took 18 months to build our WRX and it was slow but it was reasonably well prepared. And then you can be taken out by someone dislodging a rock, or hitting a kangaroo on the transport stage first thing in the morning.
Rallying is a very tough sport. What these blokes do is awe inspiring. It requires massive amounts of work and even more passion. What you see on TV does not get within the same galaxy as to how tough it really is and the amount of preparation needed.