"One of" always takes the plural.
It's hard to actually pick the "fastest" car because there are bunch of different categories. The land speed record is held by, IIRC, some sort of rocket car that set a record out in the desert in Utah...but it's not clear whether that should actual count as a "car," since it wasn't actually steerable. On the other hand, it has wheels.
There are also records for drag racers and similar specialized cars that race in a straight line. And there are records for "indy car" and "formula 1" racers, which are purpose built race cars that have steering and other features not usually considered optional on actual cars people drive. And then there are stock cars, which are based on cars that you could actually buy at a dealership (although internally I think they are quite different). And then of course there are the cars you buy at the dealership and don't modify at all.
And then of course there is the issue of distance - fastest over 1/4 mile; fastest mile; fastest 500 miles. Or time - fastest hour; fastest 24 hours. Or acceleration: fastest 0-60 speed; fastest 0-100 speed.
There are a lot of "fastest" cars...
I would say "made" instead of "to be made," though.