1998 Mazda 626 2.5L V6 LX Edition
 

Can someone explain how a vacuum gauge works and what the numbers mean. I am wanting to purchase a vacuum gauge for my car but need to know what numbers to maintain and which numbers to stay away from. Right now I do 50%/50% driving in town and freeway/highways. I joined fuel mileage web site and recorded all my mileage and right now I get 28.5 mpg at 0.11 cents per mile. Thank you for your time.

A vacuum gauge can be used in two ways:

1. To tell you when you are stepping on the gas pedal too hard and therefore driving too fast/hard. You would try to keep your vacuum high. In my opinion you could just use your foot and your speedometer for this, but some people find it to be a useful addition.

2. For people like me who use a heavy-throttle technique to reduce pumping losses and avoid wasting energy creating a vacuum, it can probably tell you when additional throttle won't make a difference. In this case, you would try to keep your vacuum low.