Welcome to the HAH club! From the other thread, it sounds like you can offer a lot of technical insight.

28mpg isn't bad, especially over a partial tank, and given the style and vehicles you've mentioned. That's about where I started. It'll take awhile to develop the techniques to get the full potential out of the car, should you choose to try that. If not, just enjoy the ride, and remember that, even below EPA mileage numbers, you are STILL using less fuel than in any other car you probably would've gotten!

The curse and blessing in a hybrid is that mpg gage. You can see your sins immediately, but are also able to use it to help you make up for them. If you have access to a OBD2 scanner, plug it in to your other cars while driving, and see what your MPG is....probably also well under EPA. It's just not apparent to most drivers, since there's no gage to look at. So hybrids get spotlighted for less-than-advertised numbers, although its a pretty similar picture for many cars.

The electric side of our cars is designed to be in a continual cycle of partial charging, discharging, charging, etc. As such, it is very rare to get a full charge. 3-4 bars is completely normal in the HAH.

The more bars, the more quickly IMA will kick in to 'help.' You'll notice this at 5 bars. 6 is Nirvana, but short-lived. Get to 2, and the engine will regen automatically when you don't normally expect it. Get to 1, and the autostop will keep the engine on even at idle until the pack is charged up.

3-4 bars is a nice spot- enough energy to give you IMA when you really need it, and enough space left to absorb several long, hard brakings.

The best advice in the HAH: once you are at/close to the speed you want to be at, KEEP THE ECO LIGHT ON. That is where the fuel savings occur in this vehicle, not with the IMA (under most conditions). This probably means staying off the cruise control unless its completely flat, and using your foot to maintain a constant throttle position instead.

Secondary: Slow acceleration and braking is better than hard, but the ECO light is the dominating condition. Try to anticipate conditions ahead to minimize acceleration and braking, coasting when you can. You sound like you're not a fan of going into N at speed- even without that you can still get EPA or better!