Complex sentence: The last Group C ATCC round winner at AIR was Allan Grice driving a VH Commodore on 1 July 1984, this was also the last ever ATCC race held under the locally developed Group C rules.
Split into simpler sentences: The last Group C ATCC round winner at AIR was Allan Grice driving a VH Commodore on 1 July 1984. This was also the last ever ATCC race held under the locally developed Group C rules.