I don't remember anybody who had a Maxima, so I can't point out a specific user. Hopefully somebody else can. It sounds like you're doing pretty well to start.
Your car should respond to normal strategies and techniques.
The most important thing to do is keep a gaslog. Click "Garage" at the top of the screen and add your car, then log every fill. Don't get too excited or bummed by a single tank; do look at long-term trends as they relate to different things you try.
The easiest, quickest, and most cost effective thing you can do is increase your tire pressure. The car manufacturer's recommended pressure is the minimum safe pressure for the tire size that came on the car when the car is fully loaded. The maximum rating on the tire is somewhat arbitrary but I like to not exceed it. Somewhere in between is your optimum pressure; mine is usually the max. Increased pressure benefits fuel economy, handling, durability, and tread life (despite the chance of some visible center wear), although in some vehicles it can can cause a harsh ride or (if overdone) bad handling.
The next strategy is to conserve momentum. Brake less, accelerate less. Roll through a fresh green light at 20mph instead of arriving at a red light at 40mph and then accelerating again. Take turns fast (only when safe and legal!) to avoid accelerating again after the turn.
Usually it is beneficial to keep your RPM down. Remember, it's not truly a "gas pedal"; rather it is an intake de-restrictor. For most of the throttle's range you control the restriction in your intake, increasing or reducing pumping loss. (In the last 10-20% the computer decides that you want power at all costs and goes into Open Loop mode, ignoring the O2 sensors and providing more fuel than necessary.) As such, a strategy that has worked well for me is to use heavy throttle and control my speed by shifting early.
Most vehicles gain fuel economy with reduced speed, especially on the highway, but I personally find it unpalatable to go any slower than necessary. I go all of the speed limit and no more.
There are plenty more techniques/strategies (and a rare few car modifications that can pay for themselves) but those are some good ways to get started.
Usually, there is more gas in the first half of the tank, so thoes numbers may not be that accurate. I log every fill-up, reset trip meter, and log mileage here. I get the receipt, and put the mileage down on it.
yea, don't get excited till you fill up. a very quick search online turns up 22/27 as the ratings for the 5 speed v6. 290 in 9 gallons (if the gauge were linear and accurate) is 32+mpg. possible but unlikely unless your "highway" is steady speed 45 mph and your "city" is 40 mph with lots of costing.
For example, the firebird has a very trapezoidal tank and the gauge doesn't correct for it. the F mark is really below 3/4, 3/4 is 1/2, 1/2 is 1/4, 1/4 is go to the gas station NOW. on the highway I can go 100 miles before the gauge MOVES, much less hits the F (3/4) mark. 300 miles by indicated 1/2 tank. 15 gallon tank, if it read linear you'd say "great, 40 mpg" but unfortunate reality is 300 miles takes about 11.5 gallons, not 7.5.
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"