Lighthack

The hack allows you to experience the light from headlights and flashing lights on the surrounding world during a daytime race, or at night the headlights will have no effect. Just press ESC during a race and enable Enable/Disable Lights. An option will appear in the menu - Day/Night race.
How to install: Run Lighthack.exe, select the game folder and click install. The installer is in German, but I think you know what you'll need to click.