I've deliberately tried to pick road cars because historic car races in GT always have a complete lack of field depth.
Citroen DS19 - innovative design, significant motorsport pedigree
Mini Cooper - innovative design, significant motorsport pedigree
Lotus Cortina - Significant motorsport pedigree.
Lancia Stratos - Significant motorsport pedigree.
Aston Martin DB5 - One of the most revered and famous designs.
Audi Quattro - 4WD
Jaguar E-Type - One of the most revered and famous designs.
Ford Sierra Cosworth - Significant motorsport pedigree.
Ford Escort MkII - Significant motorsport pedigree.
Ford Falcon GTHO Phase III - Once the fastest 4-door in the world. One of the most revered Australian cars.
Holden HK Monaro - One of the most revered Australian cars.
Ford Mustang - One of the originals, not a Mach 1 or a tuner.
BMW 2002 Turbo - First turbocharged production car.
Mercedes-Benz C107 SLC - Motorsport pedigree, from a variant of Mercedes' most popular designs.
Lotus Seven
Jaguar XK120 - Significant motorsport pedigree.
Fiat 131 Abarth - Significant motorsport pedigree.
Toyota 2000GT - Pioneering car from Japan.
Datsun 240Z - Pioneering car from Japan.
Iso Grifo - Former fastest production car.
Ferrari 365 GTB/4 Daytona - Former fastest production car.
Ferrari 288 GTO - Former fastest production car.
Bugatti Veyron Super Sport - Fastest production car.
The topic said historic or important. Not fictitious.