Rally Race with no headset?

Solution 1:

Left and right on the D-pad will flash an arrow on the screen, however my driver didn't appear to find this very useful on the one occasion I have tried it (I didn't realise when I started the race that my headset was dead).

There doesn't appear to be any granularity in the arrows - you either have an arrow on or off, so trying to guide someone to turn slightly can be difficult.

Solution 2:

You still have the usage of the Left/Right buttons to tell the driver when to turn and in which direction.

However it's still a lot less accurate than a real voice-chat ;)

Note also that if you want to do Rally Race only for the trophy/achievement, a lot of players are doing it in really short race so they already know the path without the copilot having to say anything.