I have a Banks iDash and have some interesting info for you guys!
I cold start the truck in my garage this past Sunday having not been driven in several days, and the Banks shows ECT (eng coolant temp), EOT (oil), and TRNS (transmission) temps all between 55-57F, which is the ambient temp in the garage. On the Banks, the ECT rises more quickly, with Oil and Trans temps warming more slowly. Get this - the factory gauge in the truck on the dash is at the 210F+ a hair mark, and on the Banks iDash ECT is at 165F, 166F, 167F climbing along as normal. The highest the Banks has shown me so far is about 199-205F. It fluctuates / changes info in real time, very high refresh rate. it's fun to watch!
I truly believe the Banks is accurate, and the factory temp gauge needle probably sits in that 210F spot from 165F thru whatever temp the fan kicks on at probably 215-220F? The average person - they just want to see that the engine temp is 'Normal' so the needle never really moves.
I've also got the Banks showing me Throttle Position %, and ECU Commanded Horsepower. Pretty interesting to look at. Take off on a highway stoplight, just a normal take off I use about 23-27% throttle. It shows 80-100HP. Once at 60mph it takes about 60HP to maintain that speed. An aggressive take off will show 240HP and like 48-56% throttle. The Banks iDash is a slick little dude... ; )