In city driving the fuel consumption of my 2001 STS (European model) is nothing I'd like to talk about in public...
but I'm really surprised by how relatively moderate the consumption is on the highway, given the enormous power this thing has. Just last week I drove 400 miles from Amsterdam to Southern Germany and really kicked it hard (AVERAGE speed of 100 mph, and going as fast as 130 mph when possible) and got 19 MPG. I've done the same trip in a more relaxed fashion (going about 80-90 mph) and got 23.5 MPG. The 25 MPG point is at about 75 mph for me.