I thought Coupe de l'Avenir has been put to bed some decades ago
I think you're right.
1980s was the decade of the series.
I believe there was a "Classic Days" revival of the cars in 2010 and there is a site dedicated to that.
The model type JB-03 also included 2000 (not a year but perhaps engine size? Strange as I thought they were limited to 1500cc). A bit of a mystery still as I don't know who constructed the car. JB may be his initials?