I was wondering about this one, may have been here before so apologies. Opel GT2.
Which led to the Silver Aero concept later, which is based on a Sportshatch - below :
note the wheel covers and modified grill shape, below:
As it is today, note no wheel covers.
Similar to the Avion.
And on a different budget, the Ferrari 512TS Modulo
And the Aston Bulldog