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How do you use the gauges on the ScanGauge? How do they help you save gas? Let's all add our ideas in one place for a reference.

Gauge | Description
MPG | Fuel Economy
CPM | Cost per Mile
GPH | Fuel Rate
VLT | Battery Voltage
FWT | Coolant Temperature
FIA | Intake Air Temperature
RPM | Engine Speed
MPH | Vehicle speed (MPH and KM/H)
MAP | Manifold Pressure (not available on some vehicles)
LOD | Engine Load
TPS | Throttle Position
IGN | Ignition Timing
LP | Open/Closed Loop


Also consider the Current, Today, Previous Day and Tank average screens. (These can be programmed into the Gauge screen if desired)

Bold to indicate my commonly used gauges.

Gauge | Description
MPG | I mainly watch this for fine-tuning throttle position on long steady uphill climbs. I use it in combination with rpm for very fine-grained speed control (finer than any mph gauges). I use the absolute minimum throttle that will maintain or slightly lose rpm.
GPH | this is the same as LOD to me - 2.0 gph is the same as about 75 LOD in my car. I prefer LOD because it has finer resolution.
VLT | watch this like a hawk while FASing with headlights on. One of my standard 4 gauges in winter.
FWT | in winter, to know when it's warmed up and I can start using the heater. I don't use the heater until it's fully warm, because that slows down the warmup process and uses more gas. In summer, to make sure it's cool enough - dump some heat with the heater if it gets too high.
FIA | check and record this at the start of any trip, for my records. I lose 1 mpg for every 3 degrees F. (below 80F - it's flat above that)
RPM | combine with mpg on long climbs. Otherwise, I don't use it. I do like to shift so I land in the next gear in the 1300-1500 rpm range.
MAP | another view of LOD/GPH. 14.7 is ambient and also full-throttle (lower pressure = vacuum = the engine is sucking air in through a restricted throttle). About 12 psi is a good point for accelerating (matches with about 75 LOD).
LOD | About 75 is good for Pulsing in a P&G routine. See the BSFC (http://www.autospeed.com/cms/A_110216/article.html) article. (75 here matches with about 12 psi MAP)
Tps | I don't use this, but it can be helpful on some vehicles - see SHM on the Prius for an example.
IGN | I don't use this, but again look at SHM.
LP | I used this once, to find out the LOD point where it goes into Open Loop. Then, I use the LOD gauge to stay below that point.


Current trip mpg average - I spend most of my time watching this gauge. I P&G all the time, and the goal is to make each glide end with a higher trip average than the previous.

Current trip max temp - in the summer, this tells me when I have too much grille blocked. I'll remove another 1/4 of it if this consistently reaches the 206-degree mark - that's when my radiator fan comes on.

Use the following to get a table. Just replace the {} with [].

{table} Gauge | Description
MPG | description
MPH | description
{/table}

Thanks, this is very useful.

I use:
LOD | For monitoring my pulses and DWLs. Pulse in the 70s on the TDI, or in the 30s on the gasser (my gasser displays lower LOD values than most).
VLT | For monitoring voltage. Critical especially in winter. FASing yourself down to a dead battery sucks.
GPH | For monitoring how much fuel the engine is actually using. I use this instead of MPG so I can directly monitor idle fuel consumption while stopped. Besides, I can quickly divide this by MPH in my head to compute instantaneous MPG.
LP | I use this on the gasser to check on whether DFCO is engaging. Needed because the GPH value takes several seconds to update on my car, whereas LP updates in a much more timely fashion. Doesn't work on the TDI.
MAP | I use this on the TDI to monitor boost pressure. Doesn't work on the gasser.


EDIT: I should add that although I have created xGauges for trip avg mpg, daily mpg and tank mpg, I rarely use them because the scangauge does not compute mpg linearly for either of my cars. This is a known problem with TDIs, and my gasser updates the data bus too infrequently to get meaningful calculations in city driving.

I use

Trip mileage--- instant mileage

in summer iat but now that is dark more i use volts for same reason as andrew does and on far right bottomm water temp. i don't like/trust the dasg guage.

cWT|Look for temps above 70C to make S4 transition.
gas|Prius gas xgauge. I like having a real number, especially on trips.
evb|Prius EV button xgauge. Beats guessing!
soc|Prius state of charge. It helps me decide how and when to use ev/stealth.