Porsche 924 Challenge Trophy
- Production: 12-13
- Date: 21 May 1978 - October 1978
- Nine rounds on English tracks between May and October 1978
- First race 21 May 1978 at Donington.
- Backed by Porsche dealers, a dozen entered cars.
- Tony Dron won the series.
- Standard car except roll cage and polishing of engines.
- Brakes were allowed cooling scoops and competition pads and linings.
- 120hp at the rear wheels (99-101hp on the standard car).
- All cars used the same Dunlop tires.