"Unfortunately, we will have to wipe both Time Trial and Time Attack leaderboards. Part of the fix for this issue involves upgrading the ghost car system so that only ghosts from patch 2 onwards will be posted to the leaderboards. This functionality is necessary to prevent players from uploading ghosts created on earlier versions of the game after patching. This change to the ghost car system will also result in locally-held ghosts from previous versions of the game being overwritten. This allows players to set new fastest times in the latest version of the game (otherwise it would be impossible to compete against times generated using the modified car setups and no one would be able to post new times to the leaderboards.
Whilst car setups cannot be modified in Time Attack modes, the second patch also fixes some other bugs that could result in bad times being generated. These other issues have been less prevalent in the Time Attack modes. However, scheduling a wipe of all leaderboards is the only means of ensuring the integrity of all of the leaderboards following the release of the second patch."
