Came across this today in an AP story by Harry Weber about BP station owners angry at the company and demanding discounts in gas to make up for what they say are customers boycotting because of the oil spill:
In recent weeks, some station owners from Georgia and Illinois say sales have declined as much as 10 percent to 40 percent.
That's just silly wording that I see too often. "As much as" defines the outer limit, and with a range where the difference is a factor of four (10 to 40), it's pointless to say it could be as much as 10 to 40. Sales have declined "as much as 40 percent" or "sales have declined 10 to 40 percent" (no need under AP style to repeat "percent" anymore).
In cases where the range is tight -- something like "sales have declined as much as 35 to 40 percent" -- it might make sense. Otherwise, no need to double up on the weasel words. Simply listing the range or using "as much as" and the outer limit, depending on the precision you want to show, is enough.