I haven't tried the pulse and glide method, but I've been using old school hypermiling techniques to get 20+ per tank. I live in a hilly area and installed large A/T tires, both of which destroy the mileage. The folks getting 24 smartly kept their stock tires.
If you're starting on a flat surface and have no one behind you (and have massive patience

) you can accelerate using just the EV motor. You can easily get up to 7-10mph on EV, which I assume saves a lot of gas along with coasting in EV. For fun I've accelerated up to almost 25mph using just the EV motor. I wish ECO mode would allow slightly more aggressive acceleration in EV before switching to the engine.
Oh, and I have noticed a slight improvement in gas mileage after 2000 miles.