S4 has a performance tuned AWD system, whereas I think the IS is just slip-based. S4 also has a bigger back seat than the current IS, available manual transmission, and split foldable rear seat-back, which I still don't understand why none of the Japanese luxury cars offer.

 

Since your going to be buying either car brand new I think the decision is VERY easy. How long are you going to be keeping the car for? If its past warranty then Lexus, and if its only up till warranty, then S4 for sure.

The S4 is significantly faster than the IS350, superior AWD system, and on a newer cycle. I think they both look great, but I would give it to the S4 in the looks department.

 

Well, not just black, but the S4, in general, is available in several bright colors that you won't find on a Lexus IS, even the F-models.

 

the car was hot, not just the color

 

Important factors to me that are Reliability, AWD system, looks, price, performance. Pretty much in that order. Everything else I have pretty much decided they are a wash or just not important enough to include.

So based on that, Lexus wins reliability and price while Audi wins performance and AWD. Style is a push IMO.

And seeing as this will be the car I get right before starting a family, I think reliability and price are going to trump the other factors. So yah I will wait to see what the '13 is350 looks like cause I'd hate to get a new '12 and see a new style pop out months after

 

Also I don't want to buy BRAND NEW. I'd like to find one with 10k miles or so on it which will be difficult with the '13 models

 

Considered a 335xi? The drivetrain is supposed to be pretty buff, MT is available and I think the DCT is available too. Going to need suspension upgrades (springs and shocks should be fine) to hang with an S4 I think, but so will an AWD IS350

I'd not do the BMW or Audi without a warranty though.

 

According to truedelta the S4 is okay at best. Why not look at something like Buick Regal GS, it isn't awd but its a fantastic car.

http://www.youtube.com/watch?v=BtqUMvsIuHk

 

As many have already posted here, European cars are very expensive to work on, maintain, etc in comparison to Lexus. There are also many non-dealer shops that simply will not work on them. Those shops that do, usually charge a premium. If you plan on ditching it when the warranty runs out, the S4 is a cool car, for sure.

When you say you care about the AWD system, what part of it do you care about? Do you think there is a big enough difference in AWD systems to matter in the specific area you care about? What AWD system will the IS350 come out with? Similar to the current 250?

Last thing is cost. S4's go for about 10k more than a current IS350...