Actually I see they have a LHD car built for a US customer...
Ariel Atom 190 Left Hand Drive
Colour: Metallic Black
Road pack, 190 Engine, Close Ratio Gearbox, Limited Slip Differential, 17" wheel pack, Competition brakes, Stainless Silencer, Stainless Fixings, Removable steering boss, Shift light steering wheel
Notes: This is a new unregistered car built for a customer in the USA who cannot now take delivery.
Ok, really wierd - I was just on their website 20 minutes ago...(looking for a new job)
I heard (forget where) that they do import cars to the US but none are street legal. The newest ones are built with a Honda S2000 engine. They have a "Road Pack" to make them UK street legal, turn signals and such, but no windshield /windshield wipers. I think that the US requires windshield wipers (see that pathetic useless ones on some Chaterams/Sevens). So you could get the engine put in here in the US to qualify as a "kit car" but the WW wipers might kill it.