Vehicles equipped with the supercharged engine have this boost gage that indicates vacuum during light to moderate throttle and boost under heavier throttle.

The gage displays the air pressure level going into the engine's combustion chamber.

The gage is automatically centered at zero every time the ignition key is turned to ON. Actual vacuum or boost is displayed from this zero point. Changes in ambient pressure, such as driving in mountains and changing weather, will slightly change the zero reading.