Just something I find confusing:

This is year 2013, computers have been generating pacenotes for quite some time (for first pass, later tweaked by humans), and somehow the rally racers still rely on paper for showing the notes in the middle of action. Why? What's wrong with audio players, HUD displays, slates/tables and all other the digital stuff?

Quote from Keling :

What's wrong with audio players, HUD displays, slates/tables and all other the digital stuff?

What's wrong with using a paper pacenote book?

Because experienced co-drivers with paper notebooks do better than GPS/any other program that could fail in a middle of a course.

paper won't stop working when the ride gets too bumpy, no screen glare, no scrolling or whatsoever, will still "work" after it falls to the ground, easier to correct in a hurry etc etc. ... sometimes low-tech is better.

It's still more reliable, simpler and faster...

Also, the guy reading your pacenotes can also fix your car.

There's two sides to this: Do you want to use more tech to supplement the co-driver or replace the co-driver with some computers?

Rally cars already have a considerable amount of kit. The co-driver already works the timing displays etc. by pressing pedals with their feet, partly because their hands are busy and partly because the controls are quite heavy and need to be placed there.

If you are thinking of removing the co-driver altogether, well sure why not. In fact if you could remove the driver too that would be ideal for engineers... But it's not a sport anymore if you do that.

if you are suggesting GPS based automatic HUD projection , you are seriously looking at the wrong sport!

because any automated system can't react to changes. crash / roll the car and chances are any auto system will need to re boot, a co driver just starts reading again, also if the weather / road condition changes from what's expected a good co driver can amend his notes and how he delivers them based on his knowlage of his driver's driving and preferences

Humans are adaptable, multi-skilled, can provide help if the car breaks down, and can assist with administration and management of the competitor's schedule and vehicle.

There is also the added element of teamwork that has been present in most forms of rallying through history. The idea of having a driver and navigator working as a crew is a well-established tradition in the sport.