The Blackbird has got an adjustable wheelbase, zero front and rear overhang and an engine that can mimic the performance qualities of everything from econo-boxes to muscle cars and in between. It only carries one person. And while it's real, it wasn't created by an established car brand; instead, postproduction house The Mill commissioned its creation because they needed an Everycar.
The car was built by J.E.M. F/X, a California-based special effects design & fabrication house that builds those utilitarian-looking, matte-black "follow-cam" vehicles you see on DVD extras. There's no word on what it cost to fabricate, but given that it "can be shot at any time, in any location, without the need to rely on a [specific] physical car" it's bound to be a long-term cost-saving measure given the budgets of car commercials these days.
We've long known that the environments most car commercials are shot in—empty highways absent any traffic, empty cities absent any traffic jams—aren't real, so the car we're seeing might as well not be real either.