Boost
Hold [Select] while choosing an area selection
at the map screen. Release [Select] when the auto-pilot engages.
Start a race, and you will be able to use a boost. Note: This
can only be done with cars that do not already have a turbo.
Foggy weather
Select time attack, free run, or vs. battle mode and
choose rain. Hold [L2] while you are selecting the track
starting point to make it foggy.
Stormy weather
Select time attack, free run, or vs. battle mode and
choose rain. Hold [R2] while you are selecting the track
starting point to make it thunder.