Annoucement here, from the New Oxford American Dictionary.

I actually know this word, because I actually do this.

"Hypermiling" is defined as "an attempt to maximize gas mileage by making fuel-conserving adjustments to one’s car and one’s driving techniques."

I do this all the time, and I expect most hybrid drivers do.  When you get below a certain mph, the gas engine cuts off and the battery takes over.  (Technically, the battery assists the engine at higher speeds, but you can't tell).  So when I drive into my neighborhood, with smaller streets and children playing, I like to lift my foot off the pedal just enough to turn off the engine.  And I silently glide through the streets and down my driveway.

More for Oxford:

Rather than aiming for good mileage or even great mileage, hypermilers seek to push their gas tanks to the limit and achieve hypermileage, exceeding EPA ratings for miles per gallon.

Many of the methods followed by hypermilers are basic common sense—drive the speed limit, avoid hills and stop-and-go traffic, maintain proper tire pressure, don’t let your car idle, get rid of excess cargo—but others practiced by some devotees may seem slightly eccentric:
• driving without shoes (to increase the foot’s sensitivity on the pedals)
• parking so that you don’t have to back up to exit the space
• “ridge-riding” or driving with your tires lined up with the white line at the edge of the road to avoid driving through water-filled ruts in the road when it’s raining

The American Automobile Assocation has issued press releases saying that certain hypermiling techniques are dangerous.  Like over-inflating your tires.  Yeah, ok.  That seems like a no-brainer to me.  Still, there is some blowback from the AAA criticisms.

Anyway, it may be less of an issue now, with gas prices under $2.00.  But I expect hypermiling to make a comeback.

Four other finalists for word of the year:

• frugalista – person who leads a frugal lifestyle, but stays fashionable and healthy by swapping clothes, buying second-hand, growing own produce, etc.
• moofer – a mobile out of office worker – ie. someone who works away from a fixed workplace, via Blackberry/laptop/wi-fi etc. (also verbal noun, moofing)
• topless meeting – a meeting in which the participants are barred from using their laptops, Blackberries, cellphones, etc.
• toxic debt – mainly sub-prime debts that are now proving so disastrous to banks. They were parceled up and sent around the global financial system like toxic waste, hence the allusion