That is a
really beautiful car.
I don't think the fabric they chose would be the most practical, though. Most modern wood/tube aircraft use doped dacron, which feels slightly less rigid than a drum top. Based on its stretchiness, I'd imagine bubbles of deformation to exist as that car drives down the freeway.
The fiber's biggest enemy is going to be the sun. I'd bet traditional dacron would only last 5-10 years constantly in the sun (w/ a UV protective coat). It would also suck for a punk with a pocket knife to "declothe" you car in a matter of minutes.
- LostCause