At 70 MPH, I get 34 mpg - It has been proven on a few different trips. Given that information, I'd like to take a vacuum reading at 70mph and then that would give me an idea of how much fuel I'd be using at whatever the vacuum pressure is.
From that, I could find the ratio between vacuum pressure and fuel consumption per hour and take the vacuum measurement at various speeds and then figure out fuel consumption per hour ... then divice how many gallons used in an hour into how many miles traveled in the hour (80 Miles \ xgallons).
I could use that to figure it out right?
Which brings me on to my next question - how do I install a vacuum gauge? I was looking at a few online and I found one that looks like the trans temp gauge I might buy over winter break. It says it comes with tubing. Does that mean that I have to put a hole in a vacuum line somewhere and then run the tubing to the back of the gauge that's mounted inside the car? How hard is this to do?