Which Gauge is Best and....
 

... why ?

fuel gauge. keeps you on the road.

Should have clarified.... :rolleyes:

What after market gauge is the best and why ?

For fuel economy, or just gauges in general? :)

In no particular order.
Fuel pressure.
Oil pressure.
A/F ratio (wideband).
Water temp.
Trans temp.
Vacuum/boost.

Even more clarification. :>)

ScanGaugeII, UltraGauge.... etc...

i have only owned the Ultragauge. for the price it can't be beat. have 2 pages with 6 or 8 readings per page. with mine being a diesel, there are a lot of readings that it won't get though. auto dim. plug-n-play except a few inputs. price. perfect size to mount on ac vent, i made a holder from soldered HD copper wire.
heard a lot of good reviews on the others though.

How much are they ?

Who has the best prices on them ?

Like 70 bucks new from Ultragauge. Just go to their website and get it direct.

From my experience SG is the winner. You can open the box and be running it in 2 minutes. It is time they released a SGIII though as it's starting to lag behind in some ways, especially for the price. But it works on most any car you might have.

UG doesn't work on my European cars or Diesels in general. Setting up all the pages will take you a while. The larger screen is neat, but might limit mounting options. It might take you a couple of weeks to go through all the settings to get it working correctly (only to give up in the end).

There's a big thread comparing the two on here already.