i agree with dropping down a gear. when u leave it in a higher gear, it just ends up dumping more fuel in, but not increasing or maintaining speed because the amount of power being produced isnt enough to propel the the weight of the car up the hill aganist the increased pull.
its just like Dudesky said with the mpg gauge. there is a resevoir here that i always have to go up. i watch that mpg gauge a lot more since i have been driving the manual. when i start going up that hill, the mpg gauge takes a nose dive.
however, in comparing different cars, my E30 325i has no problem getting up most hills easily in whatever gear and maintaining speed. my wifes subaru tho is a different story. going up that reservoir in the same gear makes the car slow down by a little more than 5mph.