I, too, was attracted to the variable cylinder management engine in the Odyssey. Makes sense that if you drive HALF the time on just 3 cylinders you SHOULD get good gas mileage.
My 2006 was in EXCELLENT condition (with 102,000 miles, only key door lock not working). I read posts that SOME Ody owners ARE getting the 20/28 MPG, but as noted in earlier post I get only 15/22. Can't say that I have tried "everything" to improve my MPG, but have yet to discover how to improve my MPG. I suspect that with some previous repair work done on the engine, being that these 21st century vehicles are so advanced/complex, someone failed to reassemble the "workings" properly.
NEVERTHELESS... I simply LOVE my 2006 Ody.