I haven't driven an Audi A8L with either engine. Driven an Audi A6 and read the reviews of the A8L vs. the Phaeton. My understanding is that they're very different cars.
The Audi has a different platform. A lot of aluminum in it, for one thing. A Phaeton has much more steel and is therefore 700 lbs. heavier, although I'm pretty amazed at how maneuverable mine is. It's got a regular and a sport transmission mode plus of course Tiptronic, and there are four suspension modes. When I've put it in sport suspension mode and sport transmission mode, I've routinely passed motorcycles on California Hwy. 1.
The Audi has a joystick to control the audio and other functions, although it's said to be a lot easier than BMW's I-drive or Mercedes COMAND. The Phaeton is buttons only. Seems like about 3,000 of them, but after a couple thousand miles in it I got the hang of it and now I really like that aspect of it. Yet I know that any car thief would be totally baffled.
Audis have considerably more spartan interiors, and that includes the A8L. This is very much a matter of individual taste. People I respect swear by Audi, but I have to say that I prefer the Phaeton's interior to the A8L. It's plusher without being over the top in any way. I think where the Audi would probably exceed the Phaeton is in the transmission, which is a six-speed as opposed to the Phaeton's five-speed.
The reviews of the Phaeton dinged it for having an uncertain shifting pattern with the 5-speed. I think I've noticed that about two or three times in one year, so to me it's not an issue. The Audi also gets better gas mileage because of the lower weight, but I say if you have a 12-cylinder car it's sort of comical to sit there and whine about gas mileage. I can never figure out why people who have high performance cars will write a review on Edmunds.com taking off points for gas mileage. I want to scream: "Get a hybrid then!"
I can tell you this much: You sure won't find a W-12 Audi with 18,000 miles on it for $53,000. Even if I thought it was a better car than the Phaeton, which based on my reading and the time spent with the A6 I don't believe, the price tag alone would send me to the VW.
I guess there's one other thing, and that's that the Phaeton is a much more beautiful design. I generally don't care that much about it, or I didn't until I got it. It's just amazing how many people have commented on the car. I've had a couple of hot cars before this one, and I've never had anywhere close to as many compliments.
Most people think it's a rather large Passat (also another nice looking car), but there's this little Phaeton cult out there that goes nuts when they see it. They come from all points on the spectrum. In a single day last year, I was pulled over by a Calif Hwy Patrol officer who had all kinds of questions about the car before concocting a warning; had a 20-something Mexican in a low rider go crazy about it when I was getting gas in San Jose, and got fawned over by a rich guy at the car wash in Carmel.
I know how much of a braggart I must sound like, but this has really been an amazing experience. I'm the last person on earth I would have expected to fall in love with a car.
