I sincerely doubt the car can retail for a mere $600, even if you have it assembled in a jailhouse with inmates working for free.
The mere cost of the parts to assemble is much beyond $600.
I also believe the car will actually be sold as a three-wheeler (it's a single seater, so why bother with automobile legislation?) hence, a motorcycle.
Last, the title says "1 liter for 100 kilos" which to me is weight, not distance.
Even if it were distance, I do not see it happening yet.
Italy is riddled with four wheelers (quads/ automobile wannabees) powered by 450cc diesel singles, but they get 50-60km/liter diesel, if they're lucky.

Incidentally, that VW's taillights look right out of a 1970's Citroen GS.