Porsche dealer. Mercedes too, Possible Ferrari dealer coming soon though.

Maserati used to be fisker

Thomas Classics, they specialize in mostly sports, exotic, and other high-end cars.
They've had many ferrari's, maseratis, lambos, porsches, bentleys, AM's, and others

Mercedes... yeaaaa

McLaren Philadelphia is expanding down to Tyson's Corner soon. Not sure if it's going to be a retailer or just a service center, but still, there should be a new place down your way for some good stuff.

It takes me about two minutes to walk to Lamborghini/Bentley/Lotus San Francisco from my school. There's a Jaguar/Land Rover dealer next to it that's pretty cool. Also my friend lives near Ferrari/Maserati Silicon Valley and McLaren/Fisker San Francisco (in Palo Alto, confusing name). Sometimes we bike to them from his house.

Other than that, this place called San Francisco Sports Cars is on my way home and I've been there once. They usually have a pretty crazy inventory.

Mercedes

Owner of McLaren SF has a red F1 (matches his Enzo).

Was that the one that was parked behind a MP4-12C Spyder or whatever in Beverly Hills.

Bob Forstner London-Zonda's, Koenigsegg's etc.
Roman's International-Enzo, Veyron, every supercar
Bugatti dealership

Basically, any car dealership is within in hour as I live in London :)

We have one street in Brisbane and in that street is the:
Ferrari
Maserati
Lotus
Bentley (and some old Rolls Royce's)
Audi
Lamborghini
Porsche
Lexus
Mercedes
All on the same street but there's also BMW and Jaguar dealers in the area I'm not sure if it's the same street though

But on the Gold Coast is Aston Martin (and Jaguar, too)

My local BMW Dealership is very friendly (Cooper BMW of York), and GC Motors of Harrogate are incredible too. I've been talking about business with them in the future, with me doing videos of their stock, which consists of many tuned Range Rovers, the odd Ferrari, Maser, AMG, Lamborghini and any R8.

When i have been to London, i have been invited into the BMW Park Lane and BMW i-car dealership too (Presenting the i8 and i3), plus i was also invited into Jack Barclay Bentley/Bugatti dealership too...incredibly nice people there. Plus, HR Owen's Ferrari Atelier at the Berkeley hotel were very nice too, and i was invited in when it had first opened in 2011.

Best Dealership for cars though in my area is of course GC Motors and Redline Supercars in Knaresborough (They're rivals though xD)

That was in SF for the start of goldRush, but yes that's the one.

Miller Motorcars.

Oh yeah, I think it was in the dealership for the first few weeks or so after it opened. Still never seen it. :/