From my experience (I'm no car expert)..
1. rpm is directly proportional to mpg. You have to play with the trip computer(TC) to understand your driving style vs. mpg. reset the TC, drive normal, look at the rpm and the TC when you accelerate from stop, drive at constant speed and when you approach any stops. I have found that if you let the rpm go higher than the 2.5x mark gas consumption gets high. That is true even if you are on the hway.
2. I am able to get 16 mpg city (95 % city and all 25 speed limit) by accelerating slowly, coasting to stops and timing stop lights to minimize stops. The biggest hit comes when you have to accelerate from a stop so you got to minimize that. I used to get 25-27 on hways but on my last trip I got 21.
3. Park in garage so you don't have to warm up the car during cold days, if any.
4. Don't keep your car running while you pick/drop kids or similar situations.
5. Inflated the tires to +3 than the recommended. I did see a 1 mpg drop with new Bridgestone Alenza tires.
6. If you have a second car that gives better mpg then use it. I do that when I have access to my second car.
7. For my MDX the fuel octane didn't make any diff in mpg and the same for type of oil. I go for the full synthetic for other reasons.
8. Replaced the old air filter which was really dirty but I didn't notice any mpg change.
After reading thru some articels on this forum I am giving my mdx the techron treatment to see if it makes any difference (currently my mdx is not accelerating smooth)
I believeing that just by following step 2 any car (not just the MDX) can get at least 40-50 miles more on a tankfull.
I very much doubt you will get 17 mpg in the city if it does not include some stretches of 35 speed limit. I should also add that by seeing the driving style of other MDX owners I sometimes wonder if its only my MDX that doesn't give the sticker mpg.
Sorry for the long email. I don't really get to contribute much on this forum