There was a time selling the Koeingsegg. I think is by Beng Seng. Concept car usally are sold by ABC brianza. But is all 1/43 scale. Quite expensive. I got myself a Ferrari Alcodor Sbarro and Alfa Romeo Dardo. They have more. Got to this website
www.abcbianza.com
you actually can download the complete catalog from there, but keep in mind, most of the kits are out of production. email them will be more safe.
As for Enzo, BBR had just released it in 1/43, and Tamiya 1/24 is coming this december. Just in time to get christmas present:hehehe: :hehehe: