I have a 2000 RX300 with 87K. I was initially getting 21-22 on the highway and 18 in the city. Our highway miles are mostly in the relatively flat parts of the Carolinas, traveling between Columbia, Raleigh & Charleston and mostly driving 80-85. When I tried driving around 75-80 instead, I noticed I could average 24 on a trip. When I tried driving 65-70, it dropped to 22-23, so I think there's a real torque efficiency in the high 70s. I've also noticed that the effects of drafting on MPG are amazing! Of course, I don't advocate doing it to the point of dangerously tailgating, although I suspect the effects of that would be off the chart. Drafting even 50 feet behind a car of similar or greater size noticeably ratchets up the MPG, although it's not something I've tried to quantify over a long trip. I think Mythbusters said that drafting even at 100 feet at 55mph, you get something like a 10% increase in fuel efficiency.
As for city driving, I live in downtown Columbia, so 90% of our city driving is the worst for MPG: block-by-block. Work, daycare, and just about everywhere we shop & eat are within 2-3 miles, mostly of city blocks. I can only assume that "city" MPG ratings generally account for a higher percentage of suburban driving than our 2-3 trips a month (cities being generally bigger than downtowns). That said, we're currently averaging 17 MPG in the city. When we were driving out to the beltline for daycare 3 days a week, we saw much longer stretches between stoplights and our MPG was a tick higher at 18-19.
All of this is a combination of my mileage-conscious driving and my wife's mileage-irrelevant driving. :) And I keep the tires at 42psi.