Many people drive and unless you are one of the "lucky" few who uses coal to heat up the boiler on your 1923 Stanley Steam car than you probably use petroleum distillate, better known as gasoline or diesel.
Unfortunately burning these fossil fuels produces carbon dioxide, a greenhouse gas, around 6 pounds of it per gallon of fuel. Try to stay with me as I go through the math, 25G fuel tank * 6lbs per gallon= Erratic weather patterns and an unhappy enviroment (and 150lbs of CO2)
We can help the Earth out if use this fuel efficiently. There is a way to drive to increase your MPGs drastically. How drastically? I have personally gotten a Ford Excursion to go from 8-9 MPG City to 19-23 MPG City. That's almost a 300% improvement! There are no modifications needed to your vehicle, BUT a vacuum guage is a helpful learning tool, plus they look cool and give the impression that you know what your doing and we can all use that.
Disclaimer: I don't take any responsibility to any harm done to yourself or your vehicle. I have done and performed the following operations daily. They are safe.
Step 1: Essentials
For this to work you'll need a few things:
Vehicle with an operational engine
Vacuum Gauge (Highly recommended)
Willingness to learn (this is no problem with the instructables crowd)
This method works for Electronic Fuel Injected and Carburetor engines. Also with Automatic and Standard transmissions.