The mileage is a big difference between full size v-8 and compact v-6. I am in the same market, but I am waiting till next year. I am thinking, crossing my fingers, that the tacoma will have the v-6 that the 2004 4runner has. 245HP!!
Anyhow, my brother in law gets 12.5 in town, and 16 on the highway with Tundra. I have heard of the v-6 tacoma getting up to 21 on the highway, and I think 17-18 around town. Hope this helps.