Kroger has a commercial out now about how, if you buy their milk, you can get ten cents off per gallon when you buy their gas. The woman in the commercial says, "at today's high gas prices, ten cents a gallon really adds up."
That is a statement worthy of Yogi Berra.
And, though it may be a total non-sequiter, you can't deny the truth of it. I think that when raises come around at work, I'm going to propose that everyone gets 10 cents an hour more, across the board. When my boss objects, I will say, "At your salary level, 10 cents an hour really adds up." He's probably too dumb to realize that it adds up the same no matter whose salary we're talking about.
Of course it adds up! That's what number do! And they add up regardless of the price of gas. The additive property of numbers doesn't change with the economy. 10 cents a gallon will still be 10 + 10 + 10 and so on, even if gas prices drop. What's more, it would be a better deal at a lower price of gas. If gas is $2.50/gallon, a dime gives you a 4% savings, whereas, at $1/gallon, you would be getting 10% off.
If the woman said, "at today's prices, 10 cents a gallon is marginally less in savings," it wouldn't sell much gas, but I'd be more impressed with the advertisers.