We had to replace our natural gas furnace recently-- funny how that happens when a foot of snow falls-- and given that our old furnace was just a couple days under 20 we opted to go with a high efficiency replacement. I admit to being a tad skeptical by nature and all the claims of '95% Efficiency' seemed very much like EPA mileage estimates. But we did it anyway, deciding on a Trane 95XV which also has a variable two-speed fan.
I just happened to pay my gas bill today and happened to see last weeks gas usage on my online statement. It looks like this:
Guess which day last week we replaced the furnace? :)
And this is during our deep freeze when the temperature reached a cool (for the Pacific Northwest) 15 degrees Farenheit.