With that gauge, in the link you sent me, you will also need the $359 the OEM (GM part number) ethanal "flex-fuel" sensor.i used there wide band never had a problem ..
http://www.zeitronix...s/ECA/ECA.shtml
Summit kit or just a good graduated cylinder. I bring a jug to fill a little in use a turkey baster to get the exact amount of fuel and water to measure the % of Ethanol.15$ kit sold at summit. check your content when you are filling up at the pump
http://www.summitrac...rts/QFT-36-E85/
you are not getting in car readings without buying the GM content sensor and the Zeitronix ECA.