I grew up in Bolivia. I believe the altitude will affect the support members of the teams the most. Most drivers are in relatively good shape. This will help get oxygen into the body. Anyone with any sort of breathing issues will be affected the most. Headaches are the first sign of altitude sickness. Once you get it, you very well may not get over it until you go back to a lower altitude. Weak and lethargic are the next two symptoms that have no place in Dakar.
There are pills that help. Available over the counter. Coca tea is comon place and does not get you high. It is legal to carry up to a kilo of Coca leaves on you with out any permits. Chewing the leaves similar to tobacco will ease altitude sickness, hunger pains, and keep you awake and does not get you high like cocaine does. Hydration is also a problem. The air in the high altitudes is very dry. It will suck the moisture right out of you. Chapped lips. Staying hydrated helps with the altitude as well.
I know of people that couldn't even walk off the airplane in La Paz without the help of oxygen. I hope the teams are prepared for all the days that they will be in the high altitudes.
As far as vehicles, we never had an issue with over heating due to the thin air and radiators. We lived at 5500 feet and often traveled over a 12,000 foot pass to get to one city or we would drop down to 1500 ft to get to another city. So jetting was always an issue. Motorcycles were affected the most. We didn't want to be too lean or rich. We didn't have any gas vehicles with fuel injection. Later on we converted everything to diesel. We had an Isuzu powered Dodge Power Wagon, an 86 Suburban with a Nissan diesel. We did a number of conversions for others as well.
Anyway, I am interested in seeing the affect of the altitude. I don't wish the sickness on anyone as I dealt with it all the time as a kid.