I agree with Ultrafilter Aphrodite/Venus would ride in a customized stretch limousine-painted cream, pink and red, heart shaped lights, velvet and satin interior.
Hermes/Mercury- No car. No plane. Just a hand made pair of Bruno Magli or Jimmy Chou running shoes-laces woven with virgin cotton and cloth of gold, sterling silver wings on the ankles.
Poseidon/Neptune-As he was also the god of earthquakes, his ride would have a killer sound system with more bass output than anything on earth.
Apollo- A customized military troop transport helicopter (the kind with fore and aft rotors). This would allow him to fly over the earth, as is his wont. To hover over dragons he wishes to battle, artists he wishes to inspire, or hot babes lying poolside. The copter would be painted in solar colors to reflect his aspect as a god of light, and his giant ego. The large interior of the copter is necessary to carry a retinue whose duty is to make music, poetry ect and tell Apollo how great he is.
Ares/Mars-Hummer. Although the god of war, he had a habit of running screaming from the battlefield at the least scratch. The hummer is the car of those who want to seem macho, but aren’t.
Athena-Also a Hummer. But, hers would be made to military specifications. It would also incorporate a state of the art computer system and a satelite dish (aimed at a series of dedicated satelites) capable of getting a broadband connection anywhere on the planet. A switch on the dashboard raises a screen on the tailgate, revealing her shield and turning tailgaters to stone. Her plates are from a series protecting the spotted owl.
Dionysus/Bacchus- Liquor delivery truck is a good guess. But, I say he’d drive a customized double decker bus. This way, he can always bring the party (including maenads) with him. The mahogany bar stocks every kind of booze known to man. His favorite beers are on tap. The upper level holds both an observation deck and a love lounge.
In Other Pantheons
Thor- An obnoxiously loud Harley. It’s been painted black and then had a gaudy lightning and storm clouds theme airbrushed on. The front fork features two large chrome goat heads.
Loki-Although very capable of changing shape and flying, Loki sometimes likes to blend in. His cars do tend to feature a two-tone black and red color scheme.
Frey-An offroad motorcycle with a golden scheme. A large boar’s head is mounted on the front fork. The entire bike has been treated so that mud and grime wash off effortlessly.
Odin-He’s also a trickster god and fond of disguises. His transport tends to be grey and to include a Tolkien reference.
Freya- Similar to Aphrodite’s. However, Freya is a nature goddess. The interior includes more wood and the seats are covered in luxurious furs. Freya is very fond of gold and jewels and the exterior is ornamented with more bling than you’ll see in a day of MTV. Freya is also leader of the Valkyries. The car is made of state of the art military composites. It looks like a celebrity limo, but even the windows can stand up to a grenade.
Bragi- An oldfashioned bookmobile.
Tyr- A dusty and dented Hummer, modified to allow for a one-handed driver.
Morrigan- A dusty and dented Hummer, all the mirrors have been adjusted so that she never sees her face.
Math Mathonwy- A richly appointed Bentley, chaufered by a beautiful virgin. The back seat is equipped with the best scanner in the world.
Balor-A beat up pick up. He rides in the bed, facing backwards just in case his eye opens.
Dianket-An ambulance with a souped up engine.
Fu Xing-The Batmobile. (Fu Xing is a god happiness and sometimes appears as a bat)
Hotei-An ice cream truck (Hotei is also a god of happiness and depicted as carrying a sack of toys which he distributes to children)
Kwan Yin-A semi. The trailer has been heavily modified and is now a mobile obstetrics and gynecology center.
The Seven Gods Of Happiness- Kwan Yin and the rest jointly own a luxury yacht made in the style of a junk. The bridge contains an ATM holding unlimited currency of all denominations. The boat has a stealth system centuries ahead of any other, advanced enough to render it invisible.