Hmmm, if you need help feel free to ask, that's part of the board.
I don't remember any cheats for light cars specifically though i think some auto generated codes could've been unlocked if you do well enough.
For the shoot the birds bonus round, survive long enough and it'll show up .
Btw, I'd personally always recommend the lego car in normal mode, since skidding can kill you very quickly and practically it just means more stuff to avoid, though if your playing tetris mode I'd recommend the original light car since that mode has no skidding and the light car will get to new levels faster.
hth.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)