To get more colors when painting your own logo move the cursor out of the painting area and hold L1 L2 R1 R2 Select. An RGB option will appear. To change these values use Left or Right and R1 Up or Down.
To race on a mirrored version of any track select a race and hold L1 R1 Select Start until the race begins.
To get a better idea of how your lego will appear on a car hold L1 R1 any direction to rotate and flip your logo.
Toggle Rear View Mirror
To turn off the rearview mirror pause the game and press L1 while holding Triangle. Do the same to get it back up.