I was given 20 K for my BA XR6T (Jan 04, 67000 ks) on a trade in for the FG. I couldnt be bothered with the whole selling process for a few hundred bucks. My advise is trade em and upgrade.
My 2004 BA XR6T gets around 14.8 to 15.2 in the city and 9.9 on the freeway. I pick up my new GF XR6T on Wednesday and from all reports they tell me that it will be better. Realistically, I don't care so long as the power output claims are right.