The Ariel Atom 500 (with the V8) is a little bit faster at 2.3 seconds 0-60. However it's not really a daily driver kind of car like the Tesla: https://www.youtube.com/watch?v=SIiWhWpzFQQ
True. However, the Ariel Atom is an lightweight, open air (no roof at all), tube frame, track-day car. You're well advised to wear a helmet while driving the Atom.
The Tesla is a 4-door sedan that you could easily use to pick up business partners from the airport. You might as well compare the tesla to a BMW HP4 (superbike).
People build it and then you can exchange money to receive one, how does that not qualify as a production car? Some are even built in the US (by TMI) and you can find them at dealerships: http://arielatom.com/locate-dealer/ A friend has one and it's perfectly legal to license, register, and drive on the street in some states. It has all the federal auto requirements like indicators, brake lights, etc. and can even pass a e-check (as long as you bought one with a catalytic converter).
Most definitions of a production car require that they are mass produced rather than made to order as well as being an original design rather than an aftermarket mod of a production car. I'm not sure of the exact sales model of the Atom 500, but wikipedia says it was a limited edition with only 25 made. Calling it a production car would be generous.
