[meyer]

I drive 50 miles on the highway to work and back each day. By over inflating my tires a little (32 lbs cold) and sticking at 65 MPH I can get 35 MPG in my V-6 Hyundia Sonata that can squeal the tires easily.

Just out of curiosity, is that a real measured 35 mpg (miles driven divided by fuel used) or based on the in-car computer's display. I suspect it's real in your case, but I've seen some people lately that are quoting what the car's computer tells them, which is an instantaneous estimate of fuel mileage rather than an actual measurement of miles driven versus fuel used.

I think it's a good idea to track mileage from fillup to fillup, and I keep a log for that specific purpose. One good indicator of approaching engine trouble (bad sensor, need for a tuneup, etc.) is when mileage starts dropping below the typical for those driving conditions. Keeping a log helps see this.

[McGruff]

I'm afraid I too lazy to calculate my mileage on paper. I use the cars readout. It appears it is filtered over the period in between resets. As soon as I get off the highway it will slowly drop down to a city mileage reading. And don't sit idling in your driveway. You can watch it go down. The best readout I ever had was reseting while going down a hill. Got 67.3 MPG until I got to the bottom. Take that you Prius pussies.