My car has this feature to do with gas mileage. You can switch between viewing your current gas mileage, how many miles you have left to drive on the tank of gas, see the last average mpg you achieved, and one other that I can't remember. I usually use the setting to see how many miles I have left on the tank of gas, mostly because it doesn't shift crazily like the setting for current gas mileage. Although that's a fun one, too, because when you let off the gas and coast you can get 99 mpg until the readout shows ----. Score! Now, if only I could coast everywhere I had to go....no more gas price crisis!
I've been experimenting a bit. It might not even work, but I've been driving back and forth to Bend every day and I set my cruise control at about 2,000 rpms. That's usually about 54 - 57 mph. I like to watch the gauge go up as I drive. Last night, after I'd driven up that monster hill to the college, the gauge read 320 miles left on the tank. When I'd reached the parkway, I drove 45 mph until I got out of town and upped it to about 56 mph. I listened to French language cd's and by the time I reached Redmond, the gauge had climbed to 345 miles left on the tank.
I also like to return library books and then go home and log on to my account to see if they've been received.
I know. Fun, right?