"As per the Time Trial Series Rules, from 2005 the 924 Racing Class and Ladies Class are not part of the Time Trial Classification for Standard Porsche vehicles anymore and class numbers previously allocated to these classes falls away.
The 2004 classes 3 and higher, are therefore moved down and classification now follows the normal numerical rule where class 1 is a slower class than class 2, etc.. Other anomalies such as specific class for a particular model, i.e. previous class 5 for 928's, also falls away and all standard cars with similar power to weight ratios now fall into the same class."