I am in the market for a used A6. Looking for a 2003/4 with less than 20,000 miles. Need advice on best way to find one. Also, any thoughts on front track vs. Quattro? 3.0 vs. 2.7T? Is one more reliable than the other? Pros/cons? Will only consider Silver or Dark Blue. I live in the Northeast and drive a lot of highway miles. Thank you!