That's pretty similar to my situation. My average efficiency is 3.3mi/kWh without concentrating much, but I've been driving hybrid/EVs for over 7 years now. It does sound like you might be using freeways for these short jaunts? That is a really good way to kill efficiency since you will spend a lot of power to get to a high speed where the car is least efficient and then lose all your momentum when you get off the freeway after a short distance. This isn't as inefficient as the car might make it out to be - but it could very well be causing your low GOM readings since the car can only average the past and will assume your future is filled with little high speed bits like this.
There is some adjustment to driving an EV efficiently, even from a hybrid. When I first got my LEAF I paid a lot of attention to all the little efficiency meters but over time learned to ignore them. That said, if you're coming from a gas car you do need some kind of meter to figure out where energy is going. In a gas car you are accustomed to hearing and feeling the engine and if you put your foot down you are instantly punished with noise. In an EV you can floor it and get up to high speed very quickly and with little fanfare.
The most useful thing to me is the raw mi/kWh bar chart (can be found in the center console under the EV category) and the Accel/Charge meter to the left of the fuel gauge. There's a notch about half way up the Accel meter if you look closely, and that is the threshold for the ECO light. All the ECO light does is stay on below that line or go off above that line. Using the meter itself gives you a better idea of how much juice is actually flowing. The car is most efficient when as little of that bar is lit up as possible, i.e. it is coasting/free-wheeling. Charge/regen is okay, but remember that you won't get as much juice back as you put out, for example: the LEAF regen efficiency is only 39%!
Another thing is to imagine you've got a big bowl of water on your lap. Do whatever it takes to prevent that water from sloshing out of the bowl. This'll force you to accelerate and brake smoothly and look further ahead, which dramatically increase efficiency. See here at 05:30... http://www.bbcamerica.com/top-gear/videos/budget-coupes-part-1/
Once you've gotten used to this stuff it's like second nature and you'll get a feel not only for how the GOM reacts but what the car actually is capable of despite what it tells you.
Good luck!
