We've had our '08 HiHy for about a month, always in ECO mode. Mostly used around town (commuting, slow to moderate freeway speed). We've consistently been getting 25 mpg. The EV mode button only seems to engage when the engine is warm at very low speeds (say 5mph or so). Getting 30mpg seems unattainable at this point, although we haven't done long road trips yet. Unless you are very light on the gas you'll pop it out of this mode. When very careful I can go about a mile on EV.