The number tells you what gear you are in. The red number tells you to prepair for that gear. When it flashes you have reached the point where you must slow down or you will risk hitting the wall.
There is an additional red dot next to your gear indicator that tells you if you are redlining. There is also a big dial called a TACHOMETER that tells you that you are redlining. I personally think the dot is pointless.
The red number (flashing or not) is the suggested gear for the approaching curve or turn.
~LoudMusic