Clues refresh:
1. When it was presented it wowed the audience who saw it.
2. It was built to race in a specific class of a specific national championship.
3. Curiously, each of its main competitors in that class has a different engine configuration.
4. It was presented at the Geneva Motorshow.
5. It is powered by a V8 engine.
6. That specific national championship was a GT championship in Europe.
Ferrari 288 GTO? Was built for a proposed Group B championship, had a V8 engine... the only other car built for that championship was the Porsche 959/961 with a TT flat-6.