[MeteorGray]

I have installed vacuum gauges in my cars since I got my driver's license in 1958. I still have one in my 2003 Jeep Wrangler. It's a great analog way to know what condition your engine is in. For instance, an abnormally low vacuum level under various conditions could indicate a vacuum leak, or worn cylinders resulting in low compression or clogged catalytic converters, none of which might be otherwise noticed at the time.

Regarding fuel economy, the vacuum gauge can be useful in keeping the driver informed of how hard the engine is working. Under cruising conditions, the lower the vacuum, the lower the fuel economy, provided, of course you're not revving up the engine to keep the vacuum high. When cruising, higher speeds come with lower vacuum levels which might indicated lower pumping losses, but wind resistance and tire and engine frictions quickly reduce fuel economy to overwhelm any benefits of lower pumping losses.


I've got an automatic tranny and usually let it do its thing in regards to shifting strategy, even when climbing hills. When accelerating, I know the reduced pumping loads as indicated by a low vacuum value can help engine efficiency, but I also know that the extra energy needed to provide rapid acceleration uses more fuel, so it's a pretty fine line to walk in that endeavor.

I've concluded that for twenty bucks, a vacuum gauge is a bargain. Besides, I'm a gauge nut and love the looks of an instrument panel full of needles and dials.